Okay, I need to catch up on my Gundam. Haven't watched anime in years.
We've got:
Gundam The Origin
Gundam Orphans
Gundam Thunderbolt
Is this correct?
If you haven't watched in years there's also:
Gundam Build Fighters
Gundam Build Fighters Try
G Reco
and maybe even Gundam Unicorn if you never finished it.
Thunderbolt & Origin are OAVs still running, so you can watch them or hold off until they finish.
Iron Blood Orphans is great, get on that. Hopefully it doesn't have the Sunrise "turns-to-shit-in-the-2nd-half" curse.
Build Fighters S1 is episodic, fight of the day pacing, but the 2nd half is pretty good with some great battles. Worth a watch.
I heard Try is bad, haven't seen it yet.
G Reco is love/hate depending on how big of a crazy Tomino fan you are, it's absolutely gorgeous though in art/animation/music.
Unicorn is nonsense story-wise, but it looks amazing and is epic and worth watching especially in that last ep. It's like the 0083/CCA of the modern day Gundam.