Hi niveaformen,
The following link should help (table towards the bottom of the page), which compares the Strategy points on each platform.
Your right in saying there are many more factors to consider however. For instance, some of the lesser well known platforms would earn you more PokerStrategy points, but player traffic may be an issue on some levels.
Similarly, multi-table'ability (is that a word?... is now ♦ ) is important, as is speed of software or even speed of game (e.g. Full Tilt's Rush if you like that sort of thing). And as you mentioned, there are player returns (rakeback, VIP systems, ad hoc promotions etc) to consider too.
My personal point of view is selecting a reliable platform with good traffic and somewhere you feel happy playing on. No point pushing yourself on a platform you don't like just to get the odd few extra points.
Good luck, let us know how you get on 
Best regards,
Bart