Based on my experience, any decent aluminum bar would be fine since most are designed for rugged off road use. Just find one that's comfortable. I found my LBS had a good selection with prices competitive with online retailers. I just set one up this spring.

Here's what I learned:

Shimano indexed shifters designed for flat bar road bikes are harder to find and more expensive compared to MTB shifters. Consider a friction shifter for the FD (I ended up going 1x9). A MTB shifter will work in the rear. Wait until you have your shifters to get your bars to make sure they fit.

If you need extra rise, get bars with rise rather that overly upright stem. If it is for commuting, a guy in my group has flat bars with a cross bar to mount lights, computers, bells, etc. They look pretty solid.

Hope that helps.