They're both interesting phones. I think the MiN3 has a superior processor and camera, stereo speakers, a more compact design, more premium build quality, fast charging and a USB-C port. On the other hand, the RN5P has a larger display and battery, and the SD636 is very similar to the SD660 in the MiN3. The RN5P will be more popular and will receive more attention from both Xiaomi and developers. The MiN3 hasn't received a global developer ROM, and the global stable ROM hasn't been updated.
Overall, I think the MiN3 is a more premium phone. However, the RN5P will be far more popular. For me, the RN5P is overly tall. I like my MiN3 because its dimensions are fairly small.
