I'd pick A Link to the Past first, but I think this is because I prefer the 2D games.
Ocarina of Time is longer probably, but both are a long enjoyment. ALttP will give you playtime because you have to fight bosses several times (unless you are a fabulous gamer) and for that, you have to trail through the dungeons again. It isn't as bad as it sounds though, it is greatly balanced between challenge and satisfaction.







