Flip a coin .. I have German Magura HS33 hydraulic Rim Brakes on my NL built-up Koga.
MAGURA - HS33 Rim Brake

WB Bicycle Gallery: Robert Clark's Koga Miyata WTR they are super ,
[and more common in Europe than here]

wait a little while Paulcomp is due to release a Made in California CNC cable disc caliper that promises to be super easy to keep in adjustment..

My Bike Friday got BB7s on it .. Im not going down mountains myself (other than the 1 the town covers) but in the Shop

we got a bike in for repair that melted the BB7 Adjuster Knobs ..

Can you fit really big 210 discs on it or restricted to 160s? discs get red hot . so bigger the better.