Last time I recorded a DB I used a Beyer M201 (hypercardioid dynamic) shoved up the bridge wrapped in foam, pointing at the fingerboard, and an AKG C414 B-ULS positioned about a foot away from the front of the bass. The M201 captured all the detail of the technique, and the 414 added a big, round, deep double bass feel. That was in a biggish rehearsal studio and came out sounding pretty good. The 414 was in cardioid mode to avoid picking up the baritone sax being recorded at the same time.
I've also used an RE-20 positioned just in front of the F-hole. It gets a good sound provided that the DB player doesn't move their instrument!