Not knowing your setup makes it hard to really give ya much help. If your shooting low poundage I'd go with a good cut on contact type head and avoid mechanicals. If your drawing back say 60lb plus you can start expanding your options and mechanicals. I have taken deer with both and at the moment are using Xecutioners the fly great I just don't like the orings. I have used rage in the past and they fly great also and if they have the cup blade retention system it is much better that the old orings. The only problem I've had is once I shoot a deer with them the body of the head is ruined, when the blade slap back its denting the where the blades sit and then the retention cup will not properly fit. There might not be a problem with the titainium version but I have not tried them.

With fixed you have many options (slick trick, muzzy, Thunderheads) just to name a few. And like what was previously said ALL will kill a deer, less things to go wrong with the fixed heads but your bow needs to be properly tuned as do your arrows and the mechanicals fly better out of the really fast bows on the market. (less planing)