Whoa, lots of Sonic songs all of the sudden.
The Green Hill one is pretty good. Some of the instruments sound a little bit more high-pitched and "ringy" than their original Sega Genesis counterparts, but other than that, it sounds pretty good.
Your Spring Yard Zone remix sounds more faithful than the Green Hill one, so I guess I'd consider that one a step up from the Green Hill one, even though that one wasn't bad.
My judgement on the Launch Base remix will be less sharp, because I grew up on the PC version of S3K, which has different music there, so the Sega Genesis counterpart of Launch Base isn't as thoroughly ingrained in my brain as the other songs you've remixed here. I think the ORG instruments in this song fit really well, even if it does sound a bit different from the original. The opening with that lower pitched instrument sounds extremely similar to the original, and that higher pitched instrument early on sounds really good with it, even if it sounds a bit different from the original. The drum beat is also very well done.
Once again, I played the PC version of Sonic 3D Blast growing up, which is a port of the Sega Saturn revamp, which has a different soundtrack than the original Sega Genesis release, so I'm not familiar with most of the music in the Genesis version, so I had to look up the original for this one. This remix is pretty good overall, although there are a couple of things holding it back from having that "Keep going! You're almost there!" feeling that I get by listening to the original. First is that the main instrument track sounds a bit lower-pitched and less smooth than the original. It also sounds a little bit more domineering over the other instruments than the original. The instrument that joins in at measure 004 sounds a lot quieter than the original, so maybe this could be improved by having the instruments a bit more balanced.
In any case, nice work. I always enjoy logging on here on a late Friday afternoon after work to see some new ORG creations to listen to. Nice way to start my weekend.