For me, if you're 4-0 down at half time in a European cup final then Gerrard is your man, if you're looking for something a bit less gung ho, I'd go Lampard.
I rated Gerrard over Lampard but it was close. For me, out of the 2, Gerrard had it all. lamps was a better goal scorer but Gerrard had the entire package of a CM
I preferred Gerrard but hated it getting reduced to an either/or debate. Both were unbelievable players. Lampard was supremely consistent and just never got injured. His stats for goals and appearances are mental.