Love the looks of GXP more then a GTP and who doesn't love a LS Motor but that being said GXP seem to have way more trans problem even though all the platforms share the same ones and often need a trans cooler. There's a bigger aftermarket for the 3800 but there's a light market for the LS. I would base a lot of it more on price..and check out what both the GXP and GTP sell for.