Competition is good and it seems that they really just did a great Job with Top SPin. I got Virtua Tennis and it's really good but they'll have to do their best to get back on top perception wise. I heard some great things about top spin on a dutch reviewing website. They compared the 2 games as well and the guy just felt that top spin progressed and felt more polished(visuals and animations) where it made a difference to how you would hit the ball(different button presses). While he did enjoy the more arcadey aspect of virtua tennis, he found that he could be very good by just using the A button.
I personally love it still though, but this is purely perception wise.