Shimano SM-RT56 6-bolt Brake Rotor

Good for the money

I bought the 180mm variant for my budget touring bike, combined with an Avid BB5 and Alhonga drop bar levers I get plenty of power, and did not overheat while descending a mountain with constant braking and roughly 105 kg total weight (me + bike and luggage), which was in the hot summer sun.
That is while we had to stop multiple times to let my girlfriend's rims cool down because her rim brakes were overheating.

Great value. I'm basically only using these for resin pads and the RT6x series for metallic pads.

Awful rotor, I've used it with Shimano Resin pads that came on M615 brakes, the bite was horrible, but that was due the pads, so I swapped to metallic pads, which wore the rotor fast, these really are just for resin pads as claimed.
They overheat fast, upgrading to Hope Tech Floating rotors made a huge difference, they did not get as hot. and had good braking performance for a logn time, it took a long time before I had to sand them with 100 Grit sand paper. I had them in 160 rear and 180 front.
they kept getting glazed.
but with the SM-RT56 it did not help at all, the rotor just kept overheating.