I view jazz as an evolving living art form, and not a museum piece, so, I will try to focus my recommendations on recent artists and music. But i will still recommend some older stuff too, that I feel may be more obscure.
It's not that I don't love all the 50's and 60's post-bop giants (Coltrane, Miles, Mingus, Dolphy, Evans, Shorter, Hill, etc. But there is so much incredible jazz being made now to discover.
ECM: I include this sort of a subgenre since so much of ECM's releases have a similar aesthetic.
Michael Formanek - great bass player lead quartet. 3 releases on ECM, with Craig Taborn on piano, Gerald Cleaver on drums, Tim Berne on sax. Complex time signatures abound, with great playing by all. Pretty progressive stuff, without being too out there. He also has a big band called Ensemble Colossus that is very good.
All the other players listed above, have their own discography, which are very good, and progressive.
Dominque Pifarely - lesser known French violinist, with excellent chops and creativity. Haven't heard all his releases, but what I have heard has been very good.
Eberhard Weber - might be better known here, but he can't get enough press, AFAIC. Colors of Chloe is brilliant, but all his releases are worth checking out.
Tomasz Stanko - Polish trumpet player, known as a free jazz innovator, but for ECM, he tends to be less out there. Still very creative.
M-Base collective: this is a school of jazz started by Steve Coleman in the 90's. It tends to quite rhythmically complex, but still retains a groove.
Steve Coleman (2014 MacArthur winner) - records in small ensembles, and larger ones. His sax playing is as good as it gets, but his composing is truly innovative. His more recent releases; Functional Arrhythmias, Synovial Joints, Morphogenesis are incredible.
Other artists to check out: Ravi Coltrane (John's son), Greg Osby, Jonathan Finlayson, David Gilmore (a guitarist but not the Pink Floyd guy), Andrew Milne, and others.
Fusion:
Iceberg - Spanish band from the 70's, lead by the great, Max Sune on guitar. Fiery, RtF influenced stuff, with great guitar and key interplay.
Alex Machacek - one of the most innovative of the modern crop of fusion guitarists. Writes and plays a quite complex version of fusion. His FAT trio recordings, and his work with Terry Bozio, and his CD [sic] are all great.
McGill/Manring/Stevens - released a few recordings in the 00's. Very intense fusion, that at times can seem a bit dissonant. But loaded with jaw dropping musicianship.
Forgas Band Phenomena - French fusion band, with keys, guitar, violin, trumpet, sax, drums. Great melodies all over their their releases.
Hiromi - Japanese fusion phenom. She's got Chops from hell, with great sense of melody.
Spaced Out - Canadian band, with one of the best current bass players, Antoine Farfad. Started as a pretty straight forward fusion band, but has added more metal influences into their heavy brand of fusion.
I like this thread. I will continue to add to it, in other subgenres in the near future.