There are too many subgenres of jazz, and too many eras, all with brilliant musicians, to get even close to naming only 1 favorite.
I listen to:
Post bop, fusion, chamber jazz*, avant-garde, M-Base, all of which have their list of genius level musicians. None of which I could put at a level above any other.
Post bop - Miles, Coltrane, Herbie, Mingus, Wayne Shorter, McCoy, Evans, and more. Fusion: Mahavishnu Orchestra, Return to Forever, Weather Report, Allan Holdsworth, Metheny, Jean-Luc Ponty, Brecker Brothers, and more. Chamber Jazz: Ralph Towner, Oregon, Eberhard Weber, Keith Jarrett, Jan Garbarek, Solstice, Michael Formenak, etc (the ECM label is loaded with artists I classify as chamber jazz). Avant-garde: The Art Ensemble of Chicago, Anthony Braxton, Cecil Taylor, Pharaoh Sanders, Ornette, Andrew Hill, etc. M-Base: Steve Coleman, Jonathan Finlayson, Ravi Coltrane, Greg Osby, Andre Milne, David Gilmore, etc.
There are also a whole bunch more, in various of the above subgenres, that are very close to the best.
Tim Berne, Alex Machacek, Gonzalo Rubalcaba, Hiromi, Craig Taborn, etc
I also listen to jazz-metal, but as great as it is, I don't quite put it at the same level as above. Bands like: Panzerballett, Counter-Work Experience, Liquid Tension Experiment, Intronaut, Planet X, etc.
*while I define chamber jazz similarly as Wiki does, their examples, for the most part, don't quite work for me.
Milt Jackson, John Coltrane, Jim Hall, Joe Pass, Ella.
Get this: in the late 50's I decided as a teen that I wanted to know what jazz was. I had enough money from my paper route to buy 2 LP's (mono, of course). With no idea what I was doing I picked "Time Out" by Brubeck and "Kind Of Blue" by Miles, probably because I liked the album covers. I mean, what are the odds that I'd pick what have become timeless masterpieces?
Big Band - Ellington, Kenton, & Buddy Rich BeBop - Dizzy Gillespie, Mel Torme' was scatin' & Ella Fitzgerald is an icon. Bop & Post Bop - Too many to list, I grew up on trio, quartet, and quintet groups. Many artists of that genre covered standards from the '30's & '40's into the '50's and '60's to include music from stage and screen. That music came from Gershwin, Cole Porter, Irving Berlin, later from Henry Mancini. Joe Morello of the Dave Brubeck Quartet was an idol, and still is. Chet Baker on trumpet, early Miles Davis, Oscar Peterson was an easy listen, Stan Getz, Bill Evans, Tom Jobim, etc... they're all good! Blues Jazz? In the '60s, Black singers like Nancy Wilson, Nat King Cole, & Lou Rawls were well received at our house. I listened to a Mose Allison album on Spotify recently. It was a nice trip down memory lane. Classic Fusion - Or what carried the label at the time, Mahavishnu Orchestra, Weather Report, Chick Corea were and are still regulars. Smooth Jazz - Tom Scott, Fourplay (and it's members individually) & Spyro Gyra who has progressed nicely over time, of whom I saw recently. Modern Fusion - Bill Bruford, Steve Gadd Band, Yellowjackets are all welcome around here.
That's about it, I'm spending time following Pianozach's thread "Classical Music for Beginners" to fill in some of the gaps I missed early on. There is always more music to be discovered.
When I first Al DiMeola many moons hence, I nearly soiled my underpants. How the hell could playing like that be real, I thought? Even if I lived to 100, I still wouldn't be able to shred like Al, Paco De Lucia or John McLaughlin.