Out of what you have listed I'd probably pick up the wrx. The matrix is too much of a dog with the big power engine, down low, think civic si but maybe worse
The mazdaspeed protege is really nice but the engine wasn't really engineered for the turbo so I see some problems a few years off.
The WRX sti looks awesome, although I don't think they are going to make it in a wagon, if that's a huge concern.
I like the MB a lot, but I wouldn't say it's a great car for the $$$, you are paying for some status there definetely.
Not sure where you're price ceiling is, but I'd also check out
-2000 Volvo V70 R wagon
- Used S4 avant
- VW Gti (maybe u can get a 337??)
HTH
-Pete
