haha sweet, now into my territory
I’m at heart a huge cell phone junkie so heres my opinion on things. I own the HTC One X, but have sat down and played with the S3 the S3 is alright BUT overall build quality just flat out sucks, for me the phone felt like it was going to break. The One X build quality was amazing best feeling phone i have ever owned. Originally I had intended on getting the S3 cause I was coming from a S2 but i opted to give the HTC a go and have not looked back to Samsung yet.
Now the whole TW Vs. Sense thing that can get drawn out for ages and ages depending on who u speak to but In my case I hated TW so much, I had a deep passion for TW on my S2, but a Custom rom fixes all that. For the vast majority of things I didnt mind Sense 4 on the One X it was pretty smooth but I have moved on from Sense on my One X and installed an AOKP rom. (Android Open Kang Project, google for it if you wanna check it out. AOKP is pure Android at its best, no TW no Sense.)
Between the 2 phones they are both top of the line current, various benchmarks shows the performance values to be simular to each other (but benchmarks dont mean all that much since they are NOT exactly reliable) they both have beautiful screens (I prefer the One X screen over the S3’s pentile matrix setup)
Benchmarks aside and with real world function, I have to say One X > S3