I went through the same exact process you are going through a few months ago, my manager wanted to replace our laptops with new, Linux-based ones and asked us what to get. I switched to a 15" MBP, being never a Mac person before.

The first week or so was painful. Mac OS wasn't as intuitive as I though it would be and it may be hard to find how to do things as a power Linux user. But after that initial learning curve, god it's good. Just the hardware itself is worth it, the feel, and of course the screen, which is one of the most important parts of a laptop I think. Finding and installing packages is OK with Homebrew (or MacPorts), not as intuitive as apt perhaps, though.

I have friends using a Thinkpad and if you ask me again today, I would definitely repeat my decision to go with the MBP. Maybe you're giving away a wee bit of Ubuntu goodness but you gain tremendously from hardware and being able to use other Mac software, which is very very good.