Well, here's a comparison of the Exynos and Tegra 2 chipsets
If the 2x scored that, the G2X which is supposed to be the same phone doesn't actually perform like that in the real world. I've played with a friends G2X and it doesn't come close to the SGS2 standard of smooth and it was vanilla or pretty close to it.
There are 3 things you have to understand here:
1. These are claimed theoretical performance specs on a Samsung marketing slide. Samsung also claimed that the hummingbird could push 90 million polys but in reality, it only pushed 40 mil. That slide is pretty much useless. Objective benchmarking and testing show the reality of the situation.
In reality, The Tegra 2 does over 71 M Tri/s and 1200 Pix/s. It also has a few neat little tricks like early Z culling and optimization to bring real-world fill rate performance up to Exynos' theoretical advertised levels.
2. We keep these devices for 1-3 years. Which company will make the best use of their hardware in that time? We're talking about Samsung vs nVidia. The original Galaxy S came out and Samsung couldn't even get the GPS working correctly for nearly a year. nVidia not only has an excellent track record for solid performance (save the G80 mobile soldier incident which was TSMC's fault). nVidia has already been working with software devs to leverage the power of the Tegra 2 while Samsung will rely on the Android developer community. Android devs usually build for the lowest common denominator. nVidia has an organized and powerful pro-Tegra initiative going software-side. Whatever extra potential that the Exynos has will, like the Hummingbird, most likely go unused while the Tegra 2 will feature a nice little library of high-quality software.
Tegra 2 and Exynos equipped devices hit the market around the same time (February 2011) and look at which SOC has the most software taking advantage of its capabilities. The Tegra 2.
Hell, you need to root and install Chainfire 3D to play the best Android games and even then it can't run all of the Tegra Zone games (which are the best available for Android devices right now). I have very little confidence in Samsung's abilities to bring software devs together and leverage the Exynos even a fraction of the degree that nVidia is leveraging the Tegra.
The worst I've had to deal with is waiting for Skype to put out a Tegra-optimized video call equipped app. I've got Fring. I've got Tango. Tegra is getting Gtalk video calling very soon and Skype was shown off on an Acer Iconia 8 months ago at CES making HD video calls.
I don't need 1080p video recording. A few other users might like that as a bullet point, but won't even use it. It's like comparing the iPhone 4's 5MP camera vs the 8MP cams in other devices... most users didn't give a CRAP about those extra 3MP.
The SGS 2 still needs high res 1080p vids transcoded to MP4s in order to play smoothly just like the Tegra 2 devices. Exynos can't even play MPEG2 encoded video and has quite a few sound codec limitations. Anything more than Baseline profile is going to go unnoticed unless the user regularly outputs video from their SGS2 onto a quality big screen. I don't know about you but I don't use my phone as the heart of my media center.
3. The display on the Photon has a higher resolution than the SGS 2. Yeah, it's not a SAMOLED, but it's damn good and quite a bit better in broad daylight. Tegra 2 is also in most of the current Android Tablets out today and most of those have 1280x800 res IPS screens. Whatever graphics capabilities the Exynos may have won't really benefit the user as much as the Tegra 2. 1080p High profile video means nothing on an 800x480 screen and by the time devices have screens that can showcase that power, most SGS2 users will be trading in their phones for the next best thing.
The performance difference is debatable but I'll stick with the Tegra. nVidia has already shown more initiative than Samsung in USING the capabilities and features of their SOC. I'll be keeping my device for the next 12-24 months and I want to enjoy it as much as possible. nVidia is already doing a better job at letting me do that. The only real weakness is the lack of NEON and nVidia is making it very attractive to deal with.
I see more comments in the Android market from users wishing they had a Tegra device than ones wishing for a SGS 2 (a good few of them from irritated non-Tegra users calling the Tegra-optimized apps Android fragmentation. Either you make software that takes advantage of the special hardware or live with the lowest common denominator's capabilities.).
At the end of the day, do you want to be the dude playing a new game/app on his phone or the guy frantically spending hours rooting and tweaking his device just to get that same game/app to work? I want to spend more time creating new apps/games/abilities for my device rather than wasting my time fiddling with Chainfire3D in order to play a game.
One last thing. Even though Tegra 2 devices didn't hit stores until early this year, the Tegra 2 was nVidia's 2010 SOC. Exynos is Samsung's 2011 SOC. Tegra Kal-el is nVidia's 2011 SOC.
The fact that nVidia's more-that-a-year-old Tegra 2 contends very well with Samsung's Exynos speaks volumes.