I can tell ya that I wouldn't get a 7. That's for sure. I have two and never use them.
The 9 however, is a no brainer. Awesome knife for sure!
The 2 is cool but like spikebot said, I prefer the 10 over the 2 most of the time.
TBL is also correct, you will need a 16 and I however prefer the 11 over the 14/24.
Now if you really want a great knife, get the 12. It's just pure sexy-ness! Ah..... I might have to take mine out and beat on it. haha
To be completely honest, you can't go wrong with any Becker, they are all awesome. But I would recommend to starting your collection off with 3 to 4 Beckers, One in each size range. Example: Get an 11, 14, or 24. Get one of the tweeners. And get one or maybe two of the large Becker's and you are set. Like the 10 and 9 or 2 and 4. Something like that.
Good luck and post pics when you get it!!