You are very right, the ultimate blowjob IS very subjective because everyone likes something different. The trick is to not only find a lady who absolutely adores having a hard cock in her mouth but can also adapt herself to your cues or learn what you like. To me, the better question is on techniques not who provides. Then it becomes more a question of who has a good reputation for loving what they do and who does it the way I want it done.
Only my opinion....never been on the receiving end of a blow job (dang) but have seen lots of preferences.