I really like the keyboard on my Sony S13.3 and it doesn't make me wish it were a Lenovo. The display has decent color gamut but the matte coating really makes it look a little bland, so it's not world's better than the T430S in terms of viewing angles and contrast (but again it does have better color gamut). Lenovo says they can't get LG to make IPS displays in 14" panel sizes that work for them, and that's why they stick with TN. But look at the Vaio Z3, it's TN but has wonderful colors. TN isn't the end of the world.
I'd lean toward the Sony. Thunderbolt peripherals are still very expensive and hard to come by.