I'm starting a running list of things I have really grown to appreciate about good, "pro" (in effect if not in fact) drummers. There are 4 or 5 guys in my town that I enjoy playing with so much that I will jump through hoops to be on their projects, and here are the reasons. They range in age from under 30 to over 60 but they all have these things in common:
1) They have great time AND feel. Time as in not rushing or dragging, feel as in knowing where to put the beat, whether to play straight or swing, etc.
2) They play balanced and with great dynamics. This means all pieces of the kit played at appropriate volume relative to each other and the song. Many younger / less accomplished drummers I have worked play too loudly on the top half of the kit (cymbals and snare) and have a wimpy kick. I need a drummer who will put their foot into that pedal and give me something solid to lock on to.
3) They bring as much kit as the gig requires - but no more. Stages around here are small. These guys realize their impact isn't made by how big their kit is, but what they do with it.
4) They prepare ahead of time. Every one of these guys does his homework, learning the material on their own time, writing out cheat notes to use on the gig, etc. Invariably they are the best prepared musician in the band (next to yours truly of course

).
5) They have a team approach to their instrument. Specifically they see themselves and the bassist as a partnership of equals, not a dominant/submissive deal. This is compared to other drummers I have worked with whose chops are phenomenal but who make it very clear -- even without words -- that they are the star of the unit and my job is to simply keep up.
6) They are fanatical about keeping their kit well maintained and tuned. Not a lot of EQ, gating or other tech trickery needed with these guys... their sounds come from their kit and are always good.
That's my short list. Feel free to add.