If the limit at chargen is 12R, then at chargen we're talking the following available:
0.25PP = Rating 1, 3R, 2 karma, 3k nuyen.
0.5PP = Rating 2, 6R, 4 karma, 6k nuyen.
0.75PP = Rating 3, 9R, 6 karma, 9k nuyen.
1PP = Rating 4, 12R, 8 karma, 12k nuyen.
If your character has Logic 3, that means (assuming unchanged rules) you can have 3 of these active at the same time. I'd go for 1-PP ones myself. Also, go for non-upgradable ones or powers you don't intend to upgrade ever. If you're all "yeah you know what, at 9 Strength I'm fine with Critical Strike 4 forever", that's a nice choice. Of course if you go for the weaker powers, your problem is that you aren't using your Magic*5 in Rating, unless you add Weapon Foci or got a good Logic. After all, with 6 Magic you can take 7.5PP max. That's 60 karma and 90k nuyen.
Or, you can spread yourself wide. Take a lot of small ones that you don't need more than 3 active of at the same time. =)