UBO is, in my opinion, the best at blocking things and customizing what's filtered, as well as finding a way to load a ton of filter lists if desired without it slowing browser startup.
The only complication there is that for Pale Moon, UBO needs to be installed from GitHub rather than the AMO, and then a separate extension needs to be installed for updates, which is available in the AMO. More info on how to do that here (Not sure how current those instructions are):
viewtopic.php?f=19&t=19024
ABPrime is more straight forward to get up and running with, just install through the PM AMO, but it's not intended for people who use a lot of filter lists (Per its developer) and so it can slow down the browser when it launches if a lot of filter lists are installed (Last I checked anyhow- It may have changed since) because that'a not what it was designed to do.
ABL, like ABPrime, is a straight forward install that is designed and maintained specifically for PM, so you can count on its long-term compatibility. It loads more quickly than ABPrime last I checked if you use a lot of filter lists. However, it suffers from some of the same limitations that Ad-Block Plus has relative to UBO, as it is a fork of ABPlus.
Honestly, it depends on how bad your brain is fried. If you can handle the extra setup stuff, UBO is my recommendation. If, because of your health issues, you need it to be as simple as possible, ABL is probably right for you
Only mentioned the last part because your question specifically asked that we consider it in our responses. Hopefully its helpful and not insensitive- it was certainly intended to be helpful and not intended to be insensitive.