Coming from an OG EVO I would definitely pick the HTC over the s3..... But I got a note now and I love everything about it. I its so much easier to type in portrait mode because of the extra width.. 
The other thing you have to consider is are you going to root the device? From my experience rooting an HTC is far easier than a samsung and there is much more support for rooted users. 
Do you really need quad core? What is the processing speed of each device? 
Have you had a chance to play with each device? Which one's come preloaded with ICS? I can tell you that I'm frantically waiting for an upgrade that has yet to come. Having owned both samsung and HTC I can say that the HTC (again in my experience) is built tougher. I can't even tell you how many times I dropped my EVO with no real damage. 
Have you done a pros and cons list about features? What about the camera?  beats audio? Gorilla glass? Free office software? Size of the battery? Same carrier? Blah blah blah. 
I would go to the one place you can find all 3 devices that actually work, and like best buy, and play with each one. But in your case I'm sure you will love whatever you get.