X makes the most power, but sounds higher pitched and I've never cared for it...all personal taste though.

H is better than true duals for power and sounds the best of the 3 options. Deeper and smoother sound over true duals.

Having a crossover does present a challenge if you need to pull the trans and have a fully welded system. My advice is to use some V band or bolt together flanges near the mufflers so you can drop the headpipes out the way.