well road shifters front shifters dont work with mtn front derailleurs. you seem to be going through different price categories/brackets. the better derailleurs(xt, xtr, dura ace, ultegra) have stiffer linkages and sealed bearings in the pulleys, this makes a difference the long run, not much when new. when new they all shift about the same in the stand. the gearing is up to you and your load that you will carry.