I voted for 4E.
My foray into D&D technically began with me trying to figure out "whiskey tango foxtot is going on?" during two final sessions of 2E before the group planned on switching to 3E which would soon release. So 3E was really my actual first D&D system. It was new and fun, and I have probably played more games using 3E's d20 skeleton than any other system. So I have a lot of fondness for it.
I liked 4E because it addressed a lot of my growing problems with 3E. I liked the mix of balance and tacitcal options. I liked its at-will cantrips and combat options. I liked its ritual magic. I liked its skill challenges. I liked its interesting and dynamic monster design. (And I think that 5E took two huge step backwards with designing their monsters.) I liked the class tiers and epic destinies. I liked the new races and classes that were introduced. I loved the Warlord and non-clerical/bardic healing. I liked its use of power sources. I liked its new cosmology and alignments, both of which evoked the mythic and folkloric inspiration. I liked a lot of the new lore that came out of 4E. I liked Nentir Vale and its Points of Light setting. It was almost like a fresh Greyhawk setting - a setting meant for plopping in dungeons and adventures - but without the baggage of Greyhawk's tremendous accumulated lore.
Finding people who wanted to play 4E, however, was a monumental task. There were a lot of people I knew who turned it down purely on internet and gameshop hearsay than had actually read it or were aware of its mechanics. When I finally found a group, we enjoyed 4E tremendously. Most have since shifted to playing 5E, but I believe that there is something of a desire to reexamine what 4E did well (if not better than 5E) now that more time has passed between 5E and the Edition Wars.