KL and AF will be merging their FFPs soon, and we don't know a lot about the outcome of that (we do know its name which is "Flying Blue"). If you also travel within Europe, it's not clever to ignore AZ (1200 base miles for flts that cross borders) and OK (comp elite upgrades).
Also you need to know that CO (especially) and DL don't give full miles for a lot of discounted Y intra-Europe booking classes across the European Skyteam partners.
CO and DL have very popular fora, where people who know the ins and outs of these FFPs will be happy to help you with them.