we've done both. we did music together in new york city when my son was just 7-8 months old. it provided an opportunity for him to be around other little kids, play, and ofcourse enjoy music, which he loves. we did kindermusik in singapore when he was 16 months and he just didnt want to participate, or rather he kept banging on the door hoping someone would let him escape. but i thought it was really good. i think they're both quite similar programs so it comes down to the quality of the teachers/environment.
i would try asking for a trial class and see what you and kiddo think. the best part was playing in a fresh way and a fun environment (as opposed to the same old same old at home) with my child since both these focus on having fun without toys, just being silly, running, jumping, singing, etc.