Tested working controllers for the Shield

So, I have a non-rooted Shield Portable and I couldn't find a comprehensive list, so here's a little something based on the controllers I own and have tested. The controllers are listed here in a vague order of usability (most usable and/or media remotes at the top, least usable/not working at the bottom). If you have any more to add, please do and I'll edit the OP.

##My personal recommendations

• For gaming: The OnLive Universal Wireless Controller is the best controller out of all the ones I personally tested. It is sensitive, sturdy, responsive, and extremely comfortable. It functions flawlessly and the media controls work in XBMC. If you prefer the Xbox-like controller arrangement, the Amazon Fire Game Controller is in (very close) second.
• For media playback: Either of the remotes for Amazon's FireTV are perfect for media playback control. It does not suffer the same sleep/shutdown bug that affects game controllers, and battery life is good.

##A note about media control

There is a known controller bug that affects every controller I tested. If you are using a wireless controller to control XBMC (or any other app), and the controllers goes to sleep or you manually shut it off, the input control freaks out and there is a constant left joystick "up-left" signal sent until a button is pressed on the Shield itself (not any other controller). I tested this in XBMC, ES File Explorer, and Nova Launcher. That's why I recommend the FireTV remotes for media control rather than the OnLive controller.

##Fire TV Stick Replacement Remote

• Working: All buttons
• Not working: None
• Price: $14.99 (Amazon link)
• Joystick arrangement: N/A
• Connectivity: Bluetooth
• Tweaks or quirks: This remote works well in both the OS and in-app. It uses the standard game controller interface, so it can function in games (but lacks joysticks, so I don't know why you'd use it). The Back, Home, and Menu buttons work as intended, as do the media controls (tested in XBMC).

##Voice Remote for Fire TV

• Working: All major buttons
• Not working: Voice search button
• Price: $29.99 (Amazon link)
• Joystick arrangement: N/A
• Connectivity: Bluetooth
• Tweaks or quirks: This remote works well in both the OS and in-app. It uses the standard game controller interface, so it can function in games (but lacks joysticks, so I don't know why you'd use it). The Back, Home, and Menu buttons work as intended, as do the media controls (tested in XBMC).

##Nvidia SHIELD Controller

• Working: All buttons + trackpad
• Not working: None
• Price: $59.99 (Amazon link)
• Joystick arrangement: PlayStation-like
• Connectivity: Wi-Fi Direct, USB
• Tweaks or quirks: Uses Wi-Fi to connect, so you need to have it enabled.

MadCatz C.L.R.T.R. for MOJO

• Working: All buttons
• Not working: None
• Price: $49.99 (Amazon link)
• Joystick arrangement: Xbox-like
• Connectivity: Bluetooth, USB
• Tweaks or quirks: None. All buttons function exactly as expected.

##OnLive Universal Wireless Controller

• Working: All major control buttons
• Not working: Record button, Player 1/2/3/4 indicator lights (always says P1)
• Price: $49.99 (OnLive link)
• Joystick arrangement: PlayStation-like
• Connectivity: Bluetooth, wireless USB adapter
• Tweaks or quirks: The controller comes with both a rechargeable battery (charge via USB) and a 2xAA battery case. Both function very well. The included wireless adapter is simply a Bluetooth dongle and can be used on a PC for other devices.

##Nyko Playpad Pro

• Working: All buttons
• Not working: None
• Price: $19.99 (Amazon link)
• Joystick arrangement: Xbox-like
• Connectivity: Bluetooth, USB
• Tweaks or quirks: In order to work with the most recent Shield firmware update, you may need to update the firmware on the controller. You can download the computer-based updater here. (It looks sketchy as hell, but it's the official link straight from the Nyko product page)

##Amazon Fire Game Controller

• Working: All buttons
• Not working: Player 1/2/3/4 lights (always off following initial pairing)
• Price: $39.99 (Amazon link)
• Joystick arrangement: Xbox-like
• Connectivity: Bluetooth
• Tweaks or quirks: The GameCircle button acts as a Menu button. Everything else functions as expected. A short timeout with connectivity issues has been reported, but I was not able to duplicate this problem.

##Microsoft Xbox 360 Wired controller for Windows

• Working: All buttons
• Not working: Player 1/2/3/4 lights (all four flash)
• Price: $33.00 (Amazon link)
• Joystick arrangement: Xbox-like (duh)
• Connectivity: USB
• Tweaks or quirks: The Xbox button functions as the Nvidia button. The Select button acts as Home, and Start acts as the Nvidia Start button.

##Microsoft Xbox 360 Wireless controller for Windows

• Working: All buttons
• Not working: Player 1/2/3/4 lights (all four flash)
• Price: $40.19 (Amazon link)
• Joystick arrangement: Xbox-like (duh)
• Connectivity: Wireless USB adapter
• Tweaks or quirks: The Xbox button functions as the Nvidia button. The Select button acts as Home, and Start acts as the Nvidia Start button.

##Red Samurai Wireless Controller

• Working: All buttons
• Not working: Player 1/2 indicator lights (always off)
• Price: $24.99 (GameStop link)
• Joystick arrangement: PlayStation-like
• Connectivity: Bluetooth
• Tweaks or quirks: Does not have a Home button, so you shouldn't rely on this one as your primary controller.

##Sony PlayStation DualShock 3 controller

• Working: All buttons
• Not working: Bluetooth connection on a non-rooted device; D-pad has been reported not working over Bluetooth
• Price: $49.99 (Depending on color choice) (Amazon link)
• Joystick arrangement: PlayStation-like (duh)
• Connectivity: USB, Bluetooth (only USB works on a non-rooted device)
• Tweaks or quirks: On a rooted device, the Sixaxis Controller app (Play Store link) can be used to enable Bluetooth connectivity for the DualShock 3. On a non-rooted device, functionality is limited to a wired connection only.

##Nyko Playpad

• Working: All buttons
• Not working: None
• Price: $19.99 (Amazon link)
• Joystick arrangement: Xbox-like
• Connectivity: Bluetooth, USB
• Tweaks or quirks: Joysticks are digital interfaces, not analog, so control using them only works in the four major directions.

##iCade 8-bitty

• Working: All buttons
• Not working: See "Tweaks or quirks"
• Price: $69.99 (Amazon link)
• Joystick arrangement: N/A
• Connectivity: Bluetooth
• Tweaks or quirks: This device shows up in Android as a keyboard and does not use standard mappings, so it cannot be used to control the OS. It is really only useful for emulator control (which it does very well).

##Gametel

• Working: All buttons
• Not working: See "Tweaks or quirks"
• Price: $19.95 (Amazon link)
• Joystick arrangement: N/A
• Connectivity: Bluetooth
• Tweaks or quirks: This device shows up in Android as a keyboard and does not use standard mappings, so it cannot be used to control the OS. It is really only useful for emulator control (which it does very well).

##Power8 MOGA Pocket

• Working: All buttons
• Not working: See "Tweaks and quirks"
• Price: $15.99 (Amazon link)
• Joystick arrangement: Xbox-like (no D-pad)
• Connectivity: Bluetooth, app required
• Tweaks or quirks: For a non-rooted Shield, the MOGA Pivot app (Play Store link) is required to pair and use the controller. The MOGA Pocket only functions in-game, and cannot be used to control the OS. As such, it has no Home, Back, or Menu buttons. Not every game with controller support is compatible with the MOGA; the Pivot app has a TegraZone-like store with a list of compatible games.

##OUYA controller

• NOT USABLE
• Working: Left and right joysticks, trackpad
• Not working: Any usable control interface
• Price: $35.00 (Amazon link)
• Joystick arrangement: Xbox-like
• Connectivity: Bluetooth
• Tweaks or quirks: R1, R2, Y, and O act as Enter; L1, L2, and D-pad left act as Menu. A, R3, L3, the Ouya button, D-pad right, down, and up do not register. This controller is not reasonably usable.

##Future controllers not tested

I have several controllers I want to personally test. Some of these have reviews up above from other people, but I'd like to verify those reviews. In no particular order:

• Nvidia SHIELD wireless controller
• Nyko Playpad
• Viaplay Bluetooth controller
• Gametel
• SteelSeries Stratus
• SteelSeries Free
• ipega Bluetooth controller
• ipega II Bluetooth controller
• Snakebyte iDroid:con
• ipega Classic GamePad
• GameStick Controller
• DRONE
• Wii U Pro Controller
• Nyko Pro Commander for Wii U

All of these controllers are collected here. I don't have the money to buy all of them, but I'll get to them when I can.