I think I'm in a pretty good position to answer this one lol
My Evo 8 is running 20psi and some supporting light mods, and would get 3-4 carlengths on my GT-R in any given gear before the GT-R came on boost. Evos love high boost and they are monsters for response and mid-range torque. If going for runs through twisties is your thing, then an Evo is pretty hard to beat. If your favourite road mostly consists of corners taken in 3rd gear or higher, a GT-R is the weapon of choice.
If you need the car as a daily, then an Evo 8 or 9 is a brilliant car. If you want a weekend toy, then I'd choose a GT-R. I always feel a sense of occasion when I get into the GT-R, it's a feeling that I've never felt in the Evo. In the GT-R every drive feels special.
You can import a very tidy Evo 8 MR for around $35K these days, where decent R34s with genuine kms will still hit you up for $50K or more to import one yourself, so that difference alone is worth considering. $15K buys an awful lot of mods