You will find people who like each type of connector. Any that is used correctly will be fine.
I went with the polarized 4mm bullets as in the red plastic housing on Sky LiPo and Turnigy LiPo batteries since I buy only the Sky Lipo batteries now.
Mainly I did't want to be soldering on the battery's leads. Its safer to solder on the ESC (no chance of a short while soldering).