For a clan war I would say high level wizards are definitely the best IMO.
For regular situations I think it depends on your clan. If you have a big clan with a lot of high level players that are on a lot then I say still go with wizards. If your clan is smaller then you might be better off just asking for archers, since most people always have some archers readily available to send out quickly.
I also like having Minions in my clan castle; they are quick and cheap for your clan mates to make, and if you get an army that doesn't have a lot of archers and/or wizards they can really bail you out.
