I've started AS french already. I've found it really fun, and interesting, because you get to do more of what you want, as opposed to boring topics like holidays and local area. Okay, there still are topics, but you can spend a lot more time doing other things.
Also, in general, pretty much everyone in the class understands basic things, so you don't have to repeatedly revise how to form the present tense.
I haven't started my other ASs yet, so I can't say whether it's the hardest, but so far I haven't found it difficult at all. I think I'll find German harder, though.