I would take moto since finger scanner is in the front.
https://www.bhphotovideo....oto_g_plus_xt1687.html

WackyWRZ
I was faced with this same dilemma last month - finding a good phone for $250 for the wife.  Stay away from the Nexus 5x.  I bought one for the wife and it was plagued with issues - and there's always the LG bootloop issue to worry about with it.  Went through 4 of them with the wife before getting rid of it.  The Moto G4 plus is a little cheaper than the G5 plus and has a bigger screen.  All the other specs are pretty comparable outside of a slightly slower CPU in the G4+.
 
What carrier are you on - as that is a big deciding factor in recommending other phones.  I ended up getting her the Honor 6x and she is very happy with it.  Battery life is great - almost 2 days and it was only $249 at Best Buy, but it will only work on GSM carriers (ATT/TMO/Cricket) not Sprint/VZW.  The Honor 8 has gone on sale recently around $260 so that's another option - again GSM only.

I would like to have the freedom to switch between AT&T and Verizon if possible, so a phone that supports most of the radio bands would be preferable. 
 
I was considering the Nexus 5X because I knew it would receive timely Android updates, but now that you mention reliability issues, I might stay away from it. It's probably good to mention that the 5X is made by LG. I had two LG G2's die due to bootlooping (first the screen started losing responsiveness, then I replaced the screen, and then one day it started bootlooping and finally died).
 
You mentioned the Moto G4+, personally I like the 5.2 screen a little more on the G5+. Probably a better camera as well. The G5+ should also have 1 more year of updates, since it's newer (Since Lenovo purchased Motorola the updates have slowed down significantly). Leaning a bit more to the g5+ at this point, but maybe I'll wait for some more recommendations before making a decision. 

The Nexus 5X is terrible. Please don't buy that phone. 

I LOVE my Nexus 5X, I've had it for over a year now and it's fantastic. I have Project Fi and plan on upgrading to the next line of Pixel phones when they are out, though.

The G5 as the 5X is almost a year old and dwindling support from its manufacturer. Also, the Nexus has a bootlooping bug which you can only fix by sending it to LG.

I'm not sure what the Oneplus is going for nowadays, but it's definitely one of the cheaper phones with high specs comparable to high end Samsung or iPhone.

You could always go for a last year's high end model on Samsung or Apple.

NazcaC2
LG G3. I have one and I just bought one on eBay for my mom for about $150 CAD total including shipping. Still a great phone.

 
Well I was able to snag one for $50 bucks on Amazon. gonna give it a go and see if its good.

Not sure which carrier you are through, but sometimes, Best Buy has phones cheaper then the carriers, if you do a monthly payment plan, that might open up the options to some more expensive phones like the Galaxy S7 which is discounted due to the Galaxy s8 dropping.