Ender 5 upgrades

I bought an Ender 5 a few months back and I've been having a blast. I've made all of the 3d printed accessories and now I'd like to start upgrading the unit. I'm already running Octopi and got a glass build plate.

To be honest there seems to be a lot of options, and I'd like to just skip ahead to the part where I get all the good stuff.

What and where should I buy:

For a self-leveler? Upgraded software and PCB?

What else am I missing out on?