Things I've used in the past:
QSM - Was alright to use although I preferred the older version
Service Now - I liked this, wasn't too complicated, it's hosted nature means running the actual system was someone else's problem
Chap I know who is very prevalent in the security world recently did a spot of work for them which to me boosts their reputation knowing him and the projects he chooses to work on.
Remedy - Meh, seemed to be overly complex and long winded to use, seemed more suited to complex change management
Current place uses something labelled up as Maximo, no idea if that's it's public product name or if it's branded Tivoli something or other, seems to be pretty similar to Remedy to be honest more geared around change management.
Wife's place uses Heat, she's done some of the admin and reporting courses but no idea how good or bad it is.