It really depends what you want out of the pipe. I ran Aaens for 1 season on my 600 and they were very trail friendly. Bottom end was slightly increased and top end was excellent, good on gas and not a lot louder than stock when I got them new... next to stock actually, quieter than a bender silencer on an SRX)
The next season I put on a set of Power, Inc. End Dumps and the machine was completely different. Noise wasn't a concern as I got one of three made 3 into 1 quiet silencers... about the same sound level as the Aaens. When I put the stingers on (3 individual silencers) to see what it sounded like, it was amazing around the yard for 10 mins... then it just got loud. Gas mileage was about 30-40 km (20-30 miles) less than the Aaens. For gas mileage stock i would get about 220-240 km per tank, I went down to 160 km (about 50 miles worse than stock) with very very safe jetting, but the power curve was a lot broader. There was more useable power all the way through where top end speed was about the same as the Aaens.
The closest pipe that you will get to PI End Dumps are the Benders. They are pretty well spot on with power levels, but jetted slightly richer and are just ever so slightly harder to clutch, but it's basically unnoticeable... long to short benders are the same as PI End Dumps for the most part.
I don't have any experience with the other pipe brands.