Really?
I like Subie. My another car, dressed like a Saab, is actually a Subie WRX. LGT Spec B does not add much to the performance mods, as far as I know as it has been discussed in the forum I visit frequently. When it is seriously modded, the EJ25 engine is great. However, for stock, I think the fuel injection in the MS6 makes it fun to drive.
If simply judging on the AWD system, I believe LGT is the winner. But for the real performance, I think MS6 will not fare too bad compared to LGT.
Another thing is the $. I believe MS6 can be had (GT version) for around 28K. LGT SB is higher.