what 3 baitcasting combos should i carry? for all bass fishing?

That's a hard question because theirs a lot to chose from and most of our inputs will be opinions and you might not have the same experience as we had with our baitcaster combo. You mentioned for all bass fishing. For me will be flippin & pitchin, dropshot and swimbait.   

If I could only have three riggs I would have to have these, 1) 6'6" or 7' MF good for most light rigging and finesse,,,, 2) 6'6" or 7' MM,,,,small to medium crankbaits  3) 7' MHF bigger lures Carolina rigg's big Cranks, jigg'n, spinner baits etc. this would be pretty basic setups but would cover most of your techniques.   

http://www.bassresource.com/bass-fishing-forums/topic/130634-rod-selection-the-basics/