Wife and I really like the Wander V2 design. Think outside the box is really cool and my second choice, while the small BCUK logo was third. Providing they come in "economy size" I'd probably grab a couple.
Keep calm and the large BCUK logo are my favorites.
I'd prefer white print on the green ones as well instead of black text which is harder to read. I don't really need subdued colors outside of the military.
Whilst I voted for 2, I would have liked to rank them as first and second preference. I really like the evolution one, and if it came in a ladies fit tshirt I would certainly buy one. The design may need fettling for female fit, it could go a bit weird if you get the design position wrong and end up with the evolving from one nipple to the other, with the second in flames...
 I'm a voting systems geek, sorry...
 T-shirt designs for ladies fit tshirts are hard...