I'm coming from an old Pre. I like what I see with the Evo. What if Sprint picks up the Samsung Galaxy II?
The only thing the Galaxy S2 brings to the table is the Super Amoled Plus display and maybe the processor, maybe because there are rumors that there will be two different version of the phone for different markets, one that has the Tegra 2, the other one that has the Exynos from Samsung.
If it's the Tegra 2, well, that's what we've seen in the Atrix already, good CPU/GPU but without any benchmarks of the new dual Snapdragon to compare it too (in final hard and software), the jury is still out which one is better.
As far as the display goes, yes, Super Amoled plus is great, but it's a lower resolution, a slightly smaller screen, and it can't do 3d.
I am sticking to the Evo 3d. I had interest in the Galaxy S2 until they officially announced the Evo 3d.