Familiar with GURPS - played a bit back in the day fantasy, scifi, horror
Maybe play a few sessions of Deadlands (Savage Worlds) as a palate cleanser and stop reading WOTC news threads and getting discouraged about future of the game and throwing dust and ashes into the air!
Storm Dungeons, Slay Monsters, Seize Treasure A fun hack 'n' slash campaign challenges heroes with clever dungeons. To get the most out of your fantasy adventures, you need a game that lets you customize and perfect characters, monsters, treasures, and traps. That's where the ready-to-play...
I'll throw a vote at Openquest. I have hammered that system into various genres at my table, with great success and lots of enjoyment for myself and my players. My (at the time) 11-year-old grandkids played alongside my 40 to 50-year-old veteran players and had a blast with it, and understood the system quite well. I've used it for Modern Pulp action (that was the one my grandkids played in, they were working for an agency ran by an adult Jonny Quest ),fantasy of course and scifi.
If you're looking for "D&D-type feel", I'm a big fan of 13th Age. And it's got free starter rules, and everything in an SRD if you want to give it a try. If you like it, buy it though - the core book is full of sidebars of designer discussion abotu why they did certain things, knobs to tweak and effects of changing rules, and the like. As well as all the IP including their default setting and the Icons. Plus the Bestiary and Bestiary II are perhaps my favorite monster books from any setting, ever. The drip lore and hooks and ideas.
The best "alternatives to current D&D" are typically older editions of D&D. The OSR is small potatoes by comparison to current D&D, but there's a lot of wild creativity going on in that space. Especially if you like the wild, weird, and strange. Old-School Essentials is currently the top dog in that space. There are others, of course, but it seems the most popular. It's a B/X retro-clone that recently came out with Advanced Fantasy which brings in the races and classes from AD&D. If you're looking for smooth, quick to play, and well supported...you can't go wrong with OSE.
For me, AIME did not resonate, whereas The One Ring did.
AIME builds on the D&D chassis -- classes and levelling up, etc. That's good because it's familiar, and so quicker to learn for most players trying a new system.
The One Ring is more work (you need to learn the new skill systen, dice system, etc.) and so it is less immediately intuitive for most players. Nevertheless, it has a really great skill system that makes you re-think what a character can do. It finds mechanical ways to implement aspects of LOTR fiction that D&D just can't -- ways to reinforce the fellowship/friendships between characters, for instance; or the ability to sit and smoke with someone in order to understand them better, and cross the barriers of language [I think that might be removed in 2e]. And also some nice touches where you can cinematically remove your helmet when you are struggling in a combat and get a sudden burst of energy.
AIME may have been played more; TOR showed insight into the source material and marked ways a game could be different from D&D but still satisfying.