The idea that a Surly Frame and a commotion frame are similar in quality is ridiculous. I had a Maxway touring frame that you couldn't ride hands free. The tubing could be anything within the 10 buck price point. Commo is well known for an extremely high level of execution. The custom part or fit is obviously not a big positive factor here, neither is the sizing range of Surly. Apparently the Pangean is more a Great Divide than a trans-am frame. So future uses might be a factor.

Which is better for you is the main issue. Fit is the key, so you want to verify that the Commo frame geometry and tubing is standard (or rider is similar to you), not something weird; if weird that you are also in that groove; and that you have the right frame size nailed. Myself, I think with no boutique parts and second hand it needs to be near perfect low miles or cheaper.

LHTs are OK low end frames with amazing marketing, so I don't blame you for feeling the pull, but any frame builder in the US can do a better job, LHTs are only special in the marketing.

Discs don't really make sense on a road touring bike, some people prefer them as a mater of taste, there is a whole long parallel thread on brakes.