The EVO versus the Galaxy SII is a closer battle, but I think the EVO still prevails. Main differences in the GS2's advantage include the Galaxy SII having a Super AMOLED Plus screen versus the EVO's super LCD display. Also, it has much more internal storage, with 16 and even 32 GB available, much more than the EVO's 4. Next, it is the thinnest smartphone ever created. Also, the Galaxy SII's processor is amazing; even though they are even in specs (1.2 GHz dual core), GSII processor has shown remarkable power, allowing the phone to be buttery smooth with no lag. Internet browsing is very fast. Last, the Galaxy SII has higher spec'd cameras, 2 MP vs 1.3 MP on the front, 8 MP vs 5 MP on the back.
Despite all this, I think the EVO still beats the GSII. Firstly, never underestimate the power of the User Interface. From what I've seen, HTC Sense 3.0 is absolutely stunning. It is both practical (with the useful lockscreen) and beautiful (with the weather animations and the Carousal effect). I believe it to be way better than Touchwiz 4.0. Secondly, the EVO display is, overall, better than the GSII. Although the Galaxy S2's Super AMOLED Plus display is stunning with amazing contrast, it has a paltry, last-generation resolution of 480x 800 pixels, WVGA. Meanwhile, the EVO touts a higher resolution screen, qHD qith 960x540 pixels. Also, the EVO's screen is Super LCD, which is certainly no slouch. Lastly, the tiebreaker, the EVO's screen is capable of displaying stereoscopic 3D. Even if you dont use this feature, 3D is becoming more common, and more games/movies will be available on it. It's probable that in the future 3D will be used more. Either way, the EVO screen has those 3 great qualities, overwhelming the Galaxy SII's screen's single strong trait. Moving on to cameras; while the Galaxy SII has a higher spec'd camera on both the front and the back, specs dont mean everything, especially on cameras. It is hard to tell how the EVO's cameras will fare, as it has yet to be released. BUT the EVO does have a dedicated camera button, which would help decrease blurriness. One of the most important specs however, is battery life. The EVO 3D sports a large 1730 mAH battery, more than the GS2's 1650. On android this is important. Also, because battery life has been the Achilles's heel of the old evo, undoubtedly HTC has put insane efforts to increase battery life on the new EVO. I predict that it will be phenomenal. On contract with sprint, the EVO only costs 200 dollars. Unlocked, it's only 500 dollars, which is 200-300 dollars less than the unlocked Galaxy S2. Lastly, the Evo can recod and show 3D which the galaxy S II lacks. This feature, ontop of all the other advantages, makes the EVO a better phone overall than the Galaxy S2.