I start. Double Agent have the best multiplayer because...

1 - Good gameplay mechanics to Spys and Mercenaries:

Spys:

* No guns and no gadgets to kill or knockout. The only useful gadget against Mercenaries for example it's the flashbang. So the player need have more skills to kill, so hide or run it's the strategy more safe. 

* Spys can't kill the Mercenaries without specific mechanics, like grab them from behind or make them fall from a big height. 

* Can break glass and lights using his OPSAT. 

* Can rush acrobatic movements, even in windows to escape. Very badass. 

Mercenaries: 

* Sniper, automatic gun, grenade laucher and flashlight. 

* Drones. 

* Can use rappel to change his position. 

* Can run very fast. 

* Sensor that make noise If Spys are close. So the player don't waste much time in find a Spy. 

* Can melee attack spys by front or spinning ( counter grab ) and also have one execution animation. 

The only thing that don't have It's Wall Mine, but If had would be broken.  

2 - Maps: 

The maps are big, but not extremely big and have many alternative routes and places to rush objectives, hide or escape. Also the levels design are much better compared with PT, CT and BL, like for example: Blackwing, Red Diamond, Dawn Waves and Boss House. 

3 - Good time for the matchs ( 20 minutes ). 

4 - Hack:

Spys can hack from a limited distance, but the download speed increase or decrease ( if the player are close or not from the server ). And i thik that it's a better concept than CT mechanic, because the Spy can't die so easily. 

5 - Extraction download: 

Spys don't have just complete the download in servers, they also need back to the extraction point ( safe zone ). So this increase adrenaline and tension for the player. Imagine for example that only left 1 mimute to extraction the download and If you fail your team lose. It's basically Mission Impossible. . 

6 - The servers ( change in colors ) are spread well in the map. Some more challenging and others more risky to the Spys.

Try explain why you think that PT, CT, DA or BL have the best multiplayer ( Spys vs Mercs ).