Evo 4g lte dev support is off the charts right now. S-Off isnt needed either as the kernal control isnt locked down by it; the EVO3D's kernal was locked down which made ROMing a pain in the ass. Its night and day with this phone as HTC got it right. Rooting is 30 seconds and very safe. There are like 6 ROMs already and a CM AOSK for it too. Only been officially out for 2 days.
I had the OG EVO and loved it but battery life was a &^&%. I had the Evo 3D and it was ok, bit of a dud and not the #1 phone last year. GPS was weak on it btw, very unlike HTC.
Now, I have the EVO 4G LTE. Its like wow...a bad ass phone. This thing is amazing. I'm a hardcore user as a traveling consultant and live off of it. Its battery is doing very well!
That being said, S3 is going to be an awesome phone too. Heres the deal, its Samsung though. Build quality is suspect. Some people don't like the plastic feel. The important part is the internal build quality. Their Radios perform BADLY and their phones are glitchy. As in permanently glitchy. Most people know this and sprint to get CM 9 on them but with LTE and special camera stuff, you're losing a lot. Remember, Samsung is famous for good hardware components and bad software and cheap plastic.
Here is where the S3 beats the EVO 4G LTE.
1- S3 GPU is a lot better, not sure if this matters a whole lot now but it is.
2- S3 has 2GB of RAM.
The EVO is equal or better in nearly all other catagories (some are personal preference though).
End of the day, EVO wins for me.
1- I LOVE the screen
2- Pentile AMOLED screens aren't top of the line and the cartoony colors get old (EVO screen is the best on any phone ever made at the moment...better than iPhone for sure...this was a big leap for HTC)
3- Sense 4 is great, I'm really pleased with it for something non-ASOP.
4- Build quality is just phenominal. It really is. I've never gotten a GPS signal so fast on any of my other phones.
5- HD Voice when LTE comes out
6- Kick stand. You think its a gimmick but its not. Trust me. How many IPAD people do you see with the funny stand/cover that props it up? Yeah, it solves all of that
7- Camera features. I have a new baby and all of the camera features are insanely usable..especially the burst mode. I love the slow-motion mode for sports training. Helping to work on your golf swing, basketball shot or fly cast...wow it comes in handy SO freakin fast watching that happen. Camera quality is on-par with iPhone 4S which is an impressive camera phone.