I am a big fan of the Garmin Rino line. They are a bit pricey but having a walkie talkie and gps in a single unit is a real nice feature!
I bought my Dad a set of Motorola MT351R Walkie Talkies and they work really well. We went on a hunt and I gave him the truck and I took the Four wheeler. We were well over 1.5 miles away from each other in thick hardwoods. About 5PM I heard shots. A couple of mins later he came on and said he had shot 2 deer. Crystal clear as of he was standing next to me. He loves them and he has them with him every time we go hunting.