A round one...
Seriously Stang, I dont think anyone can honestly say what is the best ball to get for you. There are so many different balls out there now with different cover stocks, weight block designs, etc... plus each person has their own different delivery and lane conditions vary between the different alleys. What works good for me might be horrible for you.
There are balls that are designed to perform better for dry lanes, heavy oil lanes, Medium oil lanes, Medium to Dry, Medium to Heavy oil, oil breakdown, and any other lane conditions.
I tell you the same thing I tell everybody else that asks me this question.
1. Talk to your fellow bowlers in the bowling alley you bowl in. Find out what they use. Find out what Pro shop they trust.
2. Go to your local pro shop and talk to the people that sell and drill the balls. If you're real lucky you have more than one bowling alley/Pro shop. If they want to make a sale they'll work with you. Tell them you want a ball but not certain of which ball. Some pro shop guys will watch you bowl a few frames to get an idea of the type of ball you can use and make some recommendations. If possible try to get a second opinion before you invest $100 or more on a bowling ball. Yes the owner of the pro shop may have a bias towards one ball manufacture and may even try to push a certain ball. Another option is to buy a used ball. Alot of people buy the newest ball out there, try it for a few weeks and decide they dont like it and trade it in at the pro shop for a new ball; what costs $150 new you might be able to get for $100 or less.
3. The best ball in the world does you no good if its not drilled properly, (thats probably why you had problems with your thumb in your old ball.)
4. What weight ball is important too. If you've been using house balls then you can probably get one thats 1 pound heavier because a ball drilled for your hand will be easier to use and will feel a little lighter than a house ball.
After all that, If you throw a straight ball then I would go with a Columbia white dot. If you have the ability to hook or curve your ball get a Brunswick Fury or Power Groove balls. I only recommend those because I use them and they work for me.