AWD, the rear suspension won't have a sway bar (which you will need to swap out anyways if you're doing the AWD swap), and it'll be cheaper because of the above mentioned things. The AWD swap is like 20 hours of work. Literally everything has to be changed.

The only way it'd be worthwhile to get the FWD car is if you got a complete wrecked WRX/STI.

Or if you don't mind doing the work and paying for the parts, get the FWD car and do a JDM swap. It's easier to pass emissions. But if you're doing a USDM wrx swap then you'll pass emissions anyway.

The JDM swaps aren't worth the money in my opinion. They make equivalent power but you can't tune it unless you spend $900 for a PowerFC. Also it's harder to upgrade because some of them have a 90degree turbo inlet.