Over the last nearly 40 years I have played every edition except for 4th, which was D&D in name only. I did buy the 4th ed PHB to give it a chance, but I hated it. I even tried Neverwinter Online briefly and still hated 4e.
Prior to 5th ed my favorite was 3rd. This was mostly because of NWN 1 & 2. 3e made for a much better game system in a CRPG, in my opinion. I played NWN for a very long time on a customized persistent world server with an awesome core group of other players, and the limited version of 3e without the bloat of all the extra books worked great.
5e has since become my favorite edition. It took much of what was good about 3e, ignored most of the mistakes made with 4e, and rekindled the interest of many people that have walked away from the hobby.
My biggest problem with 5e is the nearly non-existant release schedule. I hate adventure paths. I only run custom sandbox settings with story lines dictated by the characters. There has been very little else published beyond the core books. I would love to see big books of fluff with little bits of crunch that are specific to one topic, such as a book for each race or a group of races. Maybe one for the common races (elf, dwarf, human, halfling) and one for the secondary races (orcs, tieflings, aasimar, dragonkin), so long as there is absolutely no mention of Gnomes anywhere! SCAG and Volo's are the only two books since the initial release of 5e that i even considered buying. However, i am looking forward to the big book of crunch later this year.
Short of being given the authority to completely re-design D&D according to my personal preferences and vision, I can't think of any reason to move beyond 5e. I can see it having a very long run, at least until the company needs to generate more revenue.
