I like doing both, for the time being anyway. Of course, there will come a time when I run out of dumbells, and this would be inevitable for most lifters I guess.
They "feel" different, and it seems to me DB bench works more chest, or works it differently, or something.
Current stats: age 38, height 6'2", bw ~96kg (211.6lbs)
Best lifts to date: SQ 155kg (342lbs), BP 102.5kg (226lbs), DL 220kg (485lbs), Clean & Press 70kg (154lbs) x 5