I usually use human nail clippers but they don't go around large claws, the small animal ones aren't generally too great but I liked these...
They went through my rabbits big claws with no effort at all
I don't like the guilitine (sp?) style ones so can't tell you if they're better or not
ETA:
Used these too at work experience, they were quite good and went through conti/french lop claws no problem not sure of the name though