I use the Srixon Z-star XV balls when they are on sale and the Titleist ProV1 X's are not. They are quite comparable, so I'd say go with whichever one is a better deal at the time. If you have a slower swing speed, I'd go with one of the other Srixon balls as they are a little bit softer.
If you are under a 10 handicap, I would avoid the reconditioned titlelist balls. If you're above a 10 handicap, you probably would never know the difference.
Source: pro golfer.