Depends what exactly they have, I've not seen a complete list yet. The Aplen Hotel fun house is a good one, so is Pirate Adventure.
Air is a great ride, but if it's busy, don't bother. They only run it on a decent cycle when it's quiet.
Once you've been on Mission Space, you'll not want to waste your time on a boring little Star Flyer every again.
The waltzer is a rather good one, but they are ten a penny in the UK, so it's not vital.
Wilde Maus XXL is over-rated if you ask me. The first two drops are fine but then it turns in to a bog standard off the peg mouse. Euro Coaster (or Christmas Coaster as they call it) is only really worth it for the cred. I wouldn't waste your money on Ice Mountain, it's a standard Revechon spinner in the dark. Alpine Thriller is actually a really good layout.... but it's a Pinfari with horrible trains and horse-collar OTSRs, so expect pain.
Not sure if it's there this year, but last year they had Air Wolf, a unique ride from Mondial that I personally found much more fun than a Top Scan.
Bayern Breaker (the Breakdance) was run on proper German settings last year, so that's on the must-do list!