I'll get to the point right away - you can't go wrong with a Miken.
Okay, so the days of the Miken Ultra II being legal are long gone. And trust me, that's a good thing. People were getting hurt. Then came the Miken Freak and Freak Plus. Damn! Talk about pop with a large and forgiving sweet spot.
Now Miken has moved on to the MV-1 SuperMax. The name says it all: SuperMax. Yes, that would relate to a heck of a lot of pop. If you're over 110 lbs. and the fence is 300, you've got a shot (especially if you're comfortable swinging an end-loaded). Of course, this bat is only legal in USSSA and backyard leagues. As of today, it's not legal in ASA or NSA. If you play in ASA of NSA, don't fret, Miken is always there to hook you up. Just go with the Freak 98. Best ASA bat around.
The key thing about Miken bats is that the ball jumps off the bat. Some people like using bats where the ball sticks to the bat, but if you have a baseball background, I would highly recommend a Miken. In other words, if you're a big fella and like to dip down and get everything into it, you might want to stick with brands where the ball sticks to the bat. If you're more of an overall athlete type and want some extra pop, go with Miken.
As far as durability goes, Miken is at the top of the list. I used a Miken Freak (original) for four years, and I had bought it used off someone who had already used it for three years. And we both played in three leagues at the time (+ tourneys).
If the bat sounds funny when you drop it, don't worry. That's just the way the Mikens sound. It should last for about 2,000 swings. The only time to worry is when the barrel cracks, but it will take a while, especially if you're not over 250 lbs.
The prices on Miken bats are very fair. The company came out of nowhere over a decade ago and they've made sure that once they had someone, they wouldn't let go. They know what they're doing. Quality seems to be their mission.
If you're looking to boost your average by at least 100 points and increase your distance by at least 25-30 ft., one word: Miken.