I've owned both at one stage of my photographic journey. I still own my T2 but sold my T3 to fund a Leica CM.
Here are some impressions that I got if memory serves me correctly.
The T2 is a 38mm, while the T3 is 35mm.
The T2 employs a dial of sorts so you can lock in scale focus. The T3 uses a button interface which I found extremely annoying. The T2 seemed faster and more seamless in this regard. This was one of the main reasons for selling my T3.
My T2 was faster and selecting focus while I lost a number of shots with the T3. Others may tell you different stories on this point. Another reason that I got rid of my T3.
The T2 has noticeable light fall off in the corners at 2.8. I much preferred the T3 lens its ability to maintain across the plane.
The T2 is rather chunky and WILL stand out in your jeans pocket, especially if dressed lightly for summer. The T3 is definetely MORE pocketable and quite handy for its size. Girlfriends may ask you if that is a T2 in your pocket or if you are just happy to see them. Lame joke I know.
The T2 is easier to keep steady than the T3 - my hands were big for the T3 and here I come back to the original point where I didn't like the interface of the T3.
In my opinion the Sonnar lens from both models can produce very contrasty images under full sun if you don't control your processing. Hence, their lens seem to be inherently higher contrast than Leica's equivalents, the Minilux and the CM. I simply adore the rendition produced by the Minilux and the CM. I still have my Minilux and sold my CM due to financial reasons. The CM has more coatings than the Minilux.
The Leica Minilux is even bulkier than the T2, with the CM about the same size as the T2. The T3 wins in size ratio compared to the other 3.
Also, you may compare the Ricoh GR series as this camera has a popular following with the 28mm lens and is also pocketable.
So, back to your original question, go for the T3 due to its pocketable nature. If you are a Contax man/lady then you will like the Sonnar rendering. I personally prefer the Summarit on the Leica equivalents.
Good luck.