XE-7s are, indeed, very smooth. They also have a tendency to have problems with oxidation on the resistive strip that couples the meter to the lens - usually an easy fix requiring only a good cleaning. A more annoying problem they're prone to is desilvering of the prism due to old, foam light seals breaking down. There is no way to fix this other than to find a prism from another camera and replace it or to replace the light seals proactively before they go bad.
Minolta made many, wonderful manual focus bodies and good, clean, working examples of each can be found if one is lucky or persistent but the OP asked which were the most reliable and that would be the SRT series. When asked which our favorites are I could easily see many different answers for many different reasons but that's not what the OP asked. Most reliable? SRT. I honestly don't know how anyone with extensive Minolta experience could answer differently. I really love many of the other Minolta bodies that have been mentioned here, but not for their reliability. I'm not looking to pick a fight here, I'm just trying to be realistic.