At this point, flashing custom roms on the devices you use everyday isn't worth it if your device has jelly bean or higher... Unless you're on a samsung device or something. I remember I enjoyed my old phone a lot more when I flashed cyanogenmod on it. It was stuck on Ecclair, but I was able to upgrade it to Gingerbread thanks to cyanogenmod. It even made the life battery a lot better.
I used to like cyanogenmod, and I had it on my tablet (samsung galaxy tab 2 10.1"), but it really turned me off when they decided to get rid of the tablet mode (having the 3 buttons on the bottom left of the screen), because it's really annoying to move my hands away from the edges of the tablet if the buttons are all in the center on the phablet mode (see image below)
I bought a newish android phone (xperia t) and I gotta say, I really like sony's android version. They don't shit it up a la samsung by adding tons of useless shit and bloat. However, I wish their notification bar had more toggles: it's missing airplane mode and brightness, which I use a lot.
I haven't tried other roms since it's a brand new phone, but I might when it "gets older". It runs really nice now, I've never had it lag on me or anything, so I am hesitant to start tweaking it. The only thing I did to it (aside from installing a new launcher) was to root it to get rid of the ads with AdAway. Below you can see my current homescreen.