Ease of use is a huge factor for me, may not be for you.
Most software has a trial version so go and give some things a shot
afa sound cards, make sure your mic pre is accompanied by a good power supply.
I use a mixer and an maudio interface w/o mic pres so they are separate.
I have both a mackie vlz pro and a behringer ub series. In theory they ought to be pretty close in sound quality (I've heard behringer copied a lot of the mackie design and even got sued...).
In practice the behringer employs a cheap power supply and the difference in the amount of noise I get using either was a rude awakening.
not sure how other behringer models stack up, either way wish I had done some more comparisons!