Which beer to cook with?

[DirtyRaver]

Now the weather has turned I think it's time for me to get out the slow cooker and make some casseroles, normally I'd make it with water/stock but it was suggested I try using some real ale instead.

So, any suggestions which one to use which gives a nice flavour, or will they pretty much be the same after a few hours on the cooker? Something I could pick up at Tesco etc. would be ideal.


Cheers!