[General Questions and Answers] The Janitor Mop:
Please do your own research and come to your own conclusion. Try your best to get some hands-on experience for yourself with both phones, and pick whatever YOU think is better.

I don't mean this in a condescending manner. I mean this in the most helpful manner possible, because asking one particular group for just their opinions is particularly dangerous.

When you come into our forum, you are going to get a ton of biased responses making it as if our phone is the bomb. Many responses will be critical of the other phone, even though a lot of those responses come from people who don't own that phone and/or haven't even used one before. Another hugely dangerous thing is that people will give you an opinion based on what THEY value, not what you value. You will get a lot of the "SGS2 feels like a toy" responses, which indicates that that person clearly prioritizes the feel of a phone. Those voices will crowd out the few voices of people with different values (like me), who would say things like "Sensation performs like a toy". People will say run a custom ROM, OC, different kernel, yada yada, and I've done all that, and in my experience the Sensation just doesn't run as smoothly as other phones.

There are other things that have made my Sensation experience less than pleasurable. It's just overall an under-spec'd phone IMO. Less RAM than most dual-cores, undoubtedly a pathetic amount of internal storage (1 GB, really?), an asynchronous dual-core that IMO was a poor decision, a screen that lacks in the brightness department (yes, resolution is nice, but brightness is not), software that was just plain and simple horribly finished (I love Sense but I cannot stand how much of a fail it was in terms of making sure it would run well and smoothly), a horrible speaker (worst I've heard on a phone), "build quality" that makes me question why people continue to praise HTC for that (death grip that is more significant than most phones, a creaky back, dust issues under the screen, and the backlight for the capacitive buttons leaks through a tiny crack on the side of the phone, a pseudo-unibody design), and more. The Sensation is overall just a good device, a 7 out of 10 in my book. The phones of now like the Galaxy Nexus, Droid Razr, and the like are far better IMO on paper, and I'm sure if I got hands-on experience I would like them more than the Sensation.

The issue is that clearly some people who value one certain set of aspects will love the phone. Another group of people who value a different set of aspects won't like it as much. That would be me: poor performance bothers me more than plastic build possibly could (I've had a plastic Samsung phone before, and while it was nothing to look at or hold, it was tough as heck). The thing is, my opinion doesn't matter, because I don't know what YOU value. YOU shouldn't base YOUR decision on what I value.

I suppose it's OK to get opinions from owners, but you HAVE to make sure you get them from both sides, and you HAVE to take them ALL with a grain of salt. Optimally, you'll gather opinions and then get some hands-on experience to see what really applies to you.