I love 2e and 4e. I've noticed a lot of people who still count 4e as their favorite are from the "started witn 2e" crowd like myself.
I like 4e, for a number of reasons
D&D has never been particularly good at noncombat, so the best noncombat has been mostly freeform RP, and 4e was spent all of its effort perfecting combat, and largely ignoring noncombat as an afterthought that we threw out anyway (just like how we threw it out in every other edition)
Every character contributes meaningfully to combat
Character optimization is a thing, but the difference between mid-op and high-op is enough for the mid-pp to still be signifigant.
When HP are used as they were always intended (i.e. not meat points) a 4e fight genuinely feels like a fight scene from a fantasy novel or movie.
The PC's while still vulnerable thanks to diminishing resources, feel genuinely like the protagonists of their story
The fluff crunch separation makes a literally staggering number of character concepts viable through refluff.
Similarly, refluff on the DM end makes DMing a breeze, because making an encounter becomes a breeze. You can make an encounter with the PDF's on a laptop in the time it takes the players to get themselves into trouble.
A functioning encounter balancing system... literally no other edition has this. Hitting the sweet spot between "the players trounce the encounter without using any resources" and "TPK, story over, everyone stop playing and having fun" is easy without having to fudge dice.
The combat, by itself, is fun enough to be a game. Even if the DM sucks, combat is still independently satisfying, meaning it's even MORE fun when the DM is good, and can make the stuff between encounters fun.