I have AS pro and SW pro but have played SW prem quite a bit at 2 of my friends homes. Both games have their place.
Both themes are attractive to non-pinheads, however AS is easier for non-pinheads to pick up and progress through therefore they find it more fun. SW is fun and interesting theme-wise but they never seem to progress very far into the game and lose interest. I don't find either any more brutal, drain-wise.
For pinheads, I think SW has much more staying power. AS has fairly simple objectives and fewer strategies you can use. SW has far more strategy and is currently far deeper. I also find the objectives better tied into the theme. The light show is far and away better on SW. SW gives me the "you can execute that mode/shot/game better than that" feeling that makes me keep pressing start.
AS is due for a code update and if it is anything like what happened with GOTG, all bets are off on which is better.
Today if I could only have one, it would be SW.