Now in terms of gameplay you can not say OOT was better because it was the same thing as MM. You had the same moves Link has as both and adult and child. And in MM you have pretty much all of adult Link's weapons so what's the difference? The masks themselves are the expansion to OOT's very good gameplay and each one adds new to the mix so once again MM is quite dominant in terms of gameplay.
Now here's the thing everyone complains about MM is the time limit which is not a problem if you just learn to utilize it correctly. I can break the forest temple without getting the fairies before day 1 ends because I turn back the clock as soon as I get the song. I can clear Snowhead in 1 day and night. So the time limit is actually only a minor thing if you know how to work with it. Practice makes... near perfect.
Charge, we've already argued to the death about this, but I don't think that the time traveling aspect of MM manages to pull it ahead in terms of absolute game play. If anything, it would downplay it, seeing as equipment has to be constantly restored whenever you replay time, and it gets quite annoying. If you fail a certain quest, you have to replay everything leading up to it, cut scenes included. The whole Couple's Mask side quest comes to mind, as well as the Romain Mask side quest. Both are easy to screw up, and you'll end up having to basically start over again. The Couple's Mask was the worst. Even with the Song of Double time, there was far too much waiting. Having to do it all over again because you messed up one detail is more of an annoyance that a plus in game play. Actually, it's more of something that makes people want to give up on a game altogether. Repeating the same thing isn't fun at all. This is a main reason why MM is looked down upon by many as the worst of the 3D titles is precisely this: The time limit is a barrier, something that keeps you from doing what you want to do when you want to do it. OoT had some of these, but they could be easily removed just by beating a dungeon or finding an item.
Of course, I had no problem with the time limit. It's what makes MM MM. But, the time limit alone is something that drags down game play to the lowest level for many, and is by itself enough to make people give up on it and dislike the entire game.