I saw Umphrey's McGee for the fist time a month or so ago - they totally blew me away. I had seen a few videos online, but until I saw them live it didn't totally click. Their new album Similar Skin is fantastic.
Tedeschi Trucks band does it all - great, tight songs, long jams, etc.
Great American Taxi is a great band in the vein of Grateful Dead - more acoustic, bluegrass influence than some others, but they do electric stuff as well.
moe. is always great live and studio albums IMO
Widespread Panic is a favorite (Jimmy Herring on guitar these days)
Yonder Mountain String Band is cool with their own Bluegrass/Jam sound
String Cheese Incident has been around a while and is solid.