There are arguments for both types (not what you wanted to hear?)
For:
Electrofrog are better for slow-moving short locomotives because they can pick up all the way across. Also, I think they look better than plastic.
Insulfrog can be installed with less wiring and fewer insulated gaps.
Against:
Electrofrog may short at the points if you have sub-standard wheels. You need an insulated gap beyond the frog in all cases except dead-end sidings (self-gapping!) and may need a gap between the points and the frog and wiring to the frog involving the switch machine.
Insulfrog have a short stretch with no pick-up; if your loco doesn't have pick-ups spaced longer than this (or if one wheel gets lifted a bit) the loco stalls. If you power the track beyond the frog you may get shorts between the two metal rails in the frog.
For DC or DCC? The short at the points or frog will shut down a DCC layout where a DC system will just have a slight hesitation.
