I'll second this, nothing has as much balls and cuts through the mix like a Warwick Thumb! The older ones are better, I've got a '94 sixer and it kicks ass! Most of it is the wenge/bubinga wood in the neck, giving them a great low/low-mid sound, but the bridge-located pickups give them punch and clarity. Musicman Stingrays work well for the same reason, a big fat humbucker closer to the bridge than the neck.
Actually, I'll put in a runner-up vote for Peavey Cirrus basses, the walnut or bubinga body models have some seriously good punch, great low B sound and feel simply fantastic! Just got one off ebay for like AU$1400 and it sounds almost as good as my Warwick! (And better than my Tobias, dammit!)
Cheers,
EG