Ah tough competition. But choosing better brand always helps u. Motorola gives u latest Android OS, while Redmi doesn't. I couldnt speak much unless you yourself know which to choose. For your reference I have compared both the products and I feel Moto is the right choice. Motorola Moto G5 Plus vs. Xiaomi Redmi Note 4 - GSMArena.com
Need to charge a l'il more no. of times, but charges quite faster
Best of Redmi Note 4
Better sunlight visibility
Rooting is officially allowed (warranty is retained)
Metal body (body of both metal phones feel premium in different ways. Either get your hands on them or check out some nice YouTube videos for a better understanding)
Cost difference (somewhat cheaper)
Complicated software/OS (may be a plus for some users, but it's always about discovering new things in case of MI phones)
Many additional software features
Battery lasts longer with each charge
Rn4 has hybrid slot but with 64GB you won't need a memory card (equals)
Moto is 5'2". RN4 is 5'5"
Acc to me Moto will be more comfortable and big enough. But the Screen-to-Body ratio is quite better in RN4.
Better have a look at an illustrative camera review (pics) for comparison. Here's a nice link.
RN4 has 4100. Moto has 3000. RN4 better here
Both have Quick Charge but Moto has quite faster version
If battery life difference and cost need not be considered by you, Moto should be overall better with build->sturdiness and experience.
One can anytime add features to stock ROMs but a heavy and a bit buggy ROM isn't great to have. That's my preference now (I'm a RN3 user btw).
Consider your preferences over the above points and make your choice