Two schools of thought on knives.
There are the old carbon steel knives that will dull quicker than the newer, often stainless, steel variety. But as long as you are aware of their nature and don't let them go too far, can be quickly "tuned up" on a good steel. I know several butchers who don't do many chickens (primarily furred critters -- cows, pigs, deer and the occasional moose) who treasure and dote over their old splotchy, discolored, carbon-steel knives, and wouldn't use anything else.
That said, the high-quality (essential, stainless or carbon steel) stainless knives can be great for fine work. They'll hold an edge longer, and can still be tuned up with a steel, but they don't respond to it as well as a carbon-steel balde. When they lose their edge there's nothing to be done but to actualy sharpen them (yourself, if you know how to do it properly, or pay a pro -- a good source for that service is to ask your local restaurant who does theirs).
Best tip is to have a knife sized right for the job you're asking it to do.
The crew at the (sorta) local butcher shop that does birds every Monday use one knife. A heavy, 8", stainless boning knife. They'll first use the tip end to open the skin on the back of the neck and peel it down to remove the skin and crop, then pull the neck of the plucked bird to extend it and use the handle end of the blade to sever the last joint of the neck. They then hold the blade by its spine with the handle resting aginst their palms for leverage to cut around the vent.
Some other posts on the topic have included suggestions of the Pampered Chef, plastic handled paring knives. I have some of them. Haven't used them on birds, but they're nice knives and would do the work around the vent very nicely. But nowhere near heavy enough to do sever the neck, even if it was wrung apart.
Something like that, and a heavier knife for the neck, if you don't mind having to keep up with two knives on a busy day, might do the trick for you. Just dont forget to keep your steel handy by.
