You can upgrade directly to the newer custom firmware. I use version 3.52 M33-4. Most people say that it's the most stable firmware since 3.03 OE-C, which I also used to use before this one

. Regarding what will "help" you the easiest, I'd have to suggest 3.52 M33-4 as well because some programs don't work with the newest 3.90 M33 that do work with the 3.52 M33. If you're wanting cutting edge/ newest firmware available with a few new features, instead of having some programs like a weather program or any homebrew that uses wifi, then 3.90 M33 is best for you, but you'll need a 1.50 kernel add-on for that one.
And you can definitely trust my experience
-DarkPacMan77-