Ok, so I've backed a lot and played quite a few I didn't back but got later.
Hellas – Epic Greek myth in space! Ran a one-off and then a campaign. The one-off was great. The campaign fell apart mostly due to players not meshing well with the setting and some vague rules issues here and there. Would recommend at least a look, especially since I think there was a revised book that came out and fixed some rules.
Conspiracy X 2.0 – Played in a year long campaign. Had a blast. Great game.
Numenera 1+2 – Got in on the ground floor on this way back. Ran a few one-offs but never a campaign. I did play in a The Strange campaign and had a good time. There are a few rules issues, like how armor scales, but the books are high quality and I'd recommend them.
Shadows of Esteren – Yes! Go buy this right now! The books are top notch in every way: art, presentation, rules, everything. The setting is awesome ghost story/weird things in the woods Celtic gothic fantasy/horror. I've backed every book in the series and loved every one. I ran a 2 year long game and everyone enjoyed it.
Ryuutama – Ran at GenCon for some friends and got them to buy the book too. Japanese game about fantasy traveling, often called Miyazaki fantasy. Wholesome and enjoyable with a few different "tones" you can set for different types of stories.
Wraith 20th Anniversary + Changeling 20th Anniversary – Got purely for nostalgia. Other than taking forever to get I really enjoyed revisiting the settings but probably will never play.
Shinobigami – Haven't gotten to play/run yet but "ninja drama game" is something my group is interested in giving a go.
7th Sea 2nd Edition – I really liked it when I ran it but my players had mixed reactions. Some really liked the more narrative nature, others hated that.
Mutant: Year Zero/Genlab Alpha/Mechatron/Elysium – Just wrapped up running a campaign that combined all but Elysium. 90% great with 10% frustrating issues. The robots seem way overpowered to have combined with the others. A little more crunch with the Ark projects would have been nice. Still, overall I'd say yeah, it's worth checking out.
Forbidden Lands + The Bitter Reach – Haven't gotten to play or run yet but the books (the FL ones as BR isn't out yet) are very nicely done and have my group excited to give it a go.
Tiny Wastelands/Supers/Beach Patrol – Ran Beach Patrol and Tiny Supers. We had fun. I'd recommend them to people looking for quick and light games to fill off nights.
House of Keys – Just recently got my books (I got both rules versions). It's a Slavic fantasy adventure. Haven't had time to read and digest it yet but looks interesting and I'm eager to see a more robust setting book.
Legacy: Life Among the Ruins (and all the add-on setting books) – All the books look gorgeous and do a good job of presenting the setting and rules. I have a small group lined up to give it a go but the holidays pushed it off a little.
Mythsea – Only read the preview stuff and I'm looking forward to the release. Might not be everyone's cup of tea, but the art is really nice.
The Midderlands + The City of Great Lunden – Great fun. My group calls it potato sack fantasy. You got your slightly above average joes in a dirty, muddy world that isn't quite right trying to make a living via "adventuring".
Fateforge – A D&D 5e setting by the Shadows of Estern guys. It's hard to sum up in just a few words but it's part sword & sorcery, part D&D, and enough different that I wanted to know more about the world. Haven't run it yet and I'm a little disappointed that they are changing the release format. The plan was for a core book, a magic book, a world book, a bestiary, and a supernatural/artifacts/planes book. Now instead they are combining the last three into smaller softback "atlases". So you get world, monsters and items all in one, but only for a specific region. I think they plan to do 9-12 of those and collect every 3 into a larger hardcover.
BESM 4e – New edition of a fun system. From what I've read so far it's still a good system and an easy recommend.
SLA Industries 2e – Only read a little of the preview material so waiting for more before I can really comment.
Heart: The City Beneath – I missed the Spire KS but picked it up at GenCon. Haven't run or played it yet but liked it so much I instantly backed this. I think I like the concept of Heart even more than Spire.
Vaesen – The art alone makes this worth a look. I'm just getting around to reading the alpha so it'll be some time before I can get to run it. I'm not expecting much new from the rules, as it's Mutant: Year Zero based and I know what that's like.
Gradient Decent (A Mothership Module) – I ran a Mothership one-off over the holidays. We had a good time and I feel good about backing this. I wish the Mothership boxed set was closer to being done, but for now the pre-release is pretty solid.
Blades in the Dark – I played in a game that lasted a few months. The other 2 players had some trouble with the system. Too narrative for them. I enjoyed it though. If you like Apocalypse Engine game derivatives and want to play bad guys it's worth a look.
The Sprawl – Hugely enjoyed. Surprisingly, the same guys that have issues with Blades really got into this one and had a good time. If what you want is to just run jobs in a cyberpunk world without a lot of support of anything outside the job, give it a go.
Tenra Bansho Zero – Only played a quick one-shot a few years ago, but I've read the books a few times and keep going back to it thinking about running a campaign.