I've started playing D&D with the Moldvay basic edition back in 1980, and have played every edition since. I currently DM 5e and really enjoy that ruleset. As I've gotten older, and my players have gotten older we've come to enjoy the simplicity of a "rules-light" edition, and modern game design.
I've transitioned away from the face to face games to a virtual tabletop, started with Roll20 and after about a year I think, I've moved to Fantasy Grounds. I would prefer the face to face games, but as we get older and folks move away it got harder and harder to line up schedules, this allows most of the old group to continue to play together.
Now to answer your questions:
I like 5e for the modern game design and the simplicity of the ruleset, most of it is logical and makes sense. I've added a new player here and there on occasion and the 5e ruleset is very easy to pick up and learn. I sometimes miss the 2e kits, or the 3e prestige classes, but if I feel i'm missing something I can always adapt if I need to.
Spelljammer is my favorite setting in D&D period. I love the idea of swashbuckling in space. I use the original setting with my own touches, as most DM's do. I tend to a bit more grim/dark, my major influences when doing homebrew or a sandbox setting like SJ, are the Black Company, the Thieves World novels, REH's Conan, Lankmahr, & HPL, and things along those lines, but I'm not opposed to tossing a little levity in there on occasion.
There's very little about SJ that I don't like, but there are a few. Some of the sillier elements I've just ignored and never use. I've never cared for the silliness of how the gnomes are portrayed. I enjoy it in the SJ novels, or the DL setting, but for me to run a game it's not what I prefer. I still use them as tinker-style gnomes, but with a bit more seriousness and less giant space hamsters. I don't use the Dohwar never cared for them, and things like that.
I use the established "cosmology" when it comes to the spheres. I created a sphere map many, many years ago with all the "cannon" spheres throughout the SJ product line (i've seen others use/adapt it over the years and make it much better), but I try to avoid the big 3, (GH, FR, & DL), and some of the more "goofy" spheres when possible.
I love the Imperial Elven Navy, the Scro, the Illithid's, The Rock of Bral, The Arcane and Neogi and the Unhuman Wars are all great stuff. I love the Spelljammer (not the box set mind you. I prefer it to be a mysterious/wondrous thing). Giff are wonderful, and in my campaigns the DL minotaurs are very much in space and are very Roman-legion themed.
The ships are great fun with the Nautiloid being my favorite. I do miss the ship to ship combat rules from the War Captain's Companion, but I'm working on a hopefully simplified set based around the ship rules that came out of Ghosts of Saltmarsh, with a few ideas from Starfinder's ship to ship combat.