There are many good choices in turkey chokes on the market today. There are several very good designers with a real variety of ideas of what makes a turkey choke pattern well. It's really all about the "internal geometry" of the choke.
It's important to match the choke with the gun and the shotshell you intend to use. Just like chokes, there are several excellent turkey loads available.
Once you've made that choice, based upon the best information you can get, it's important to give the choke, the shell and your gun a chance to prove themselves. Some chokes, most frankly, shoot better after a few rounds have been put down range. All too often I've heard or read where a shooter tried a choke with one or two shots and decided it didn't work.
Purchasing a gun, ammunition or a choke tube is really an investment. Like any investment, it may need some time to pay dividends or to grow in value.
I recommend that you "deep clean" your bore and choke tube http://allaboutshooting.com/article_info.php?articles_id=282 and then shoot several rounds, the more the better without cleaning between the shots.
I recommend that you shoot until patterns either improve or degrade. It's best to fire at least 10 shells. That will help you overcome ordinary inconsistencies in the shells and also really give you an opportunity to see how everything works together. It's truly the only way you'll be able to tell how your combination works with a clean, slightly fouled and dirty bore and choke tube. You may be surprised at the results.
Lastly, I understand that turkey shells are expensive. Again, think of the expense of the shells as an investment in your future. All the time and energy you put into a hunt can come down to just one shot at that prized gobbler. It's worth the money to find out now, before the season, what works for you.
I also understand that turkey loads kick. When shooting those loads, I recommend that you use a good recoil pad, like a Limbsaver, or just use a big towel against your shoulder to help reduce the recoil. Be sure to wear ear plugs and some muffs if you have them. They help keep you from damaging your hearing and can also help prevent your developing a flinch when shooting these heavy loads.
Shoot at some big paper and make it a fun experience, not a chore. Invite a friend or family member to shoot some. You're evaluating the gun, choke and ammo, not the shooter. Make it one more part of your hunting experience and maybe a way to introduce a friend or family member to turkey hunting.
I can help you select a choke that I know, from experience, works with your gun and the shells you want to use. Just email firstname.lastname@example.org and I'll get right back to you with the best advice I have. It's always a free service with no obligation whatsoever. I've been doing that for several decades now and really want to be of help to you.
Good shooting and have fun learning more about your gun, choke and ammo choice.