I like the Browning outdoorsman fillet knife. Its not too thin for cutting through wing bones, and cuts pretty nice. I used it on my South Dakota pheasant hunt this year. I cut probably 40-50 birds without even the slightest sign of becoming dull. The big perk was that it was not too expensive.
You can find it a few places on line such as
www.knife-depot.com ,
www.thesportsmancave.com, or
www.discountsportsmanstore.com. Just do a search and you should be able to find it at a good price.