So I bought HTC One S

[sanibel]

And now T-Mo is offering the Samsung Galaxy S III.

Should I..............................?

 

[Metroid Prime]

I'd say enjoy your One S because you can't really go wrong with either devices and both devices are very nice and high end if you ask me.
The One S and S3 are both really great phones and you'll be happy with either one.
Both HTC and Samsung make great phones so I wouldn't worry about it.
I'd say nice choice getting the One S if you ask me. :thumb:

 

[Stuntman]

I was so tempted to pick the third one.

There will always be a newer phone that will come out shortly after you buy one. If you can't handle it, then do #3.