I'd say insane - the biggest builds, and the parkour - while challenging - feels really accomplishing when you beat it (I'm bad at parkour I find beating Fridge and Avengers to be an accomplishment don't @ me). I always tend to ragequit on hard maps because they are very not fun, medium maps are too varied in difficulty (some easier than easy maps, some harder than hard maps) and the easy maps, while they are mostly cool, get pretty boring. Expert comes in a close second but I feel like they aren't as satisfying to beat as insane maps.