Mid Handicappers are generally looking for distance higher loft. The Titelist Pinnacle line is designed to go farther and higher and is for players with a slower swing speed.
The best golf balls for a mid-handicapper would have to be mid feel golf balls. The mid feel golf balls provide good distance and control. These golf balls have a low spin rate and are great for shorter games.
Well this depends on the person. For me the ones I like to use are. Srixon Z-URC Golf Balls, Titleist Pro V1 Golf Balls 2008, and Bridgestone Tour B330-S. There is a good price range for them as well.
Any brand of distance golf ball is good, I prefer the Nike One. These balls are great for distance and work well on the green if your short game is good. I like these balls because they hold up to use, so I can play them more than one round.
Titleist has the largest market share of most golfers at all levels. They have a wide variety of different types of balls to fit most golfer's games. Other companies such as Top Flite and Wilson have quality golf balls too, but Titleist is considered the one to beat.
Everyone can benefit from a urethane 3 piece ball such as a Titleist ProV, however, not everyone wants to spend $40+ on a dozen. Midline balls like the Titleist NXT Tour, TaylorMade Burner TP, & Callaway's HX series are under $30, and perform quite well with most all golf swings.