Krabik,
A good starting point is the compare lenders section of [broken link removed]. It's for first time buyers, but it gives you a good idea of the main points to take into consideration.
Other than that, I think it mainly comes down to things like loan to value ration and the various discounts/options the various banks offer, if you're going on a fixed rate or a discount 1 year fixed rate what rate can you go on after, etc..
Another thing at the moment - if you're going for a fixed rate, you want to make sure that your loan offer guarantees it for a while as the ECB is likely to hike up the rates soon. This is sometimes referred to as "booking a rate".
If you want to take a 100% mortgage and need to borrow the deposit as well, you want to inquire about interest and possibility of a bridging loan.
You should also check if you can make additional payments into your mortgage account if you wish, and then i think someone mentioned it before the penalties if you want to get out of a fixed rate early or if you want to pay off the mortgage early.
A bit all over the place, but it should give you some ideas!