Best hardware (laptop) for Linux audio production?

I'm running Ubuntu Studio and Ardour on my aging HP laptop, and I'm considering getting something better.

When I bought the laptop I wasn't doing anything with audio production and was on a tight budget. Now that I do more with audio (and a bit with video) I'd like something more powerful.

I travel a lot for my job so a laptop is much preferred. Any tips for good, midrange machines or specs I should look out for?