Just a tip... You can create short Amazon URLs for most items like this...
https://www.amazon.com/dp/B072N3WT4J
...where the part at the end is the ASIN number from the product information section of the page. They also have an even shorter domain amzn.com but some reddit forums block them as spam.
I purchased an X4 in October of 2017 and I'm still using it. I have no regrets whatsoever.
However, if you do get and X4, there are two things to be aware of...
Two of my friends bought X4 phones shortly after I bought mine and they both fast charge while I only use the slow charger from my old Motorola Droid 3 with a USB to USB C cable that I got for a few bucks on Amazon.
Both of my friends' phones have swollen batteries, one of them bad enough that she recently replaced it with a Moto G Power. If you look at their phones from the side, the screens bulge slightly in the middle and the glass is separating on the sides.
As an aside, she really likes the Moto G Power so far. The battery life is insane.
I did not order this one but I found this on Amazon yesterday:
https://www.amazon.com/Spigen-Rugged-Resilient-Absorption-Carbon/dp/B072N3WT4J/
Definitely disappointed at the lack of very slim cases - I ended up ordering this one:
https://smile.amazon.com/gp/product/B0761V9BDK/ref=od_aui_detailpages00?ie=UTF8&psc=1
https://www.amazon.com/dp/B072N3WT4J/ref=cm_sw_r_cp_apa_i_qlNICb8WBNABX
This is the one I have
Is the Spiegen case this one?
+1 for the Spigen
There aren't many "brand" cases available for the X4 right now
I got a Spigen Rugged Armor, I tend to drop my phone quite a bit and I've never had issues with it, it's not bulky but gives good protection. https://www.amazon.com/Spigen-Rugged-Resilient-Absorption-Carbon/dp/B072N3WT4J/ref=sr_1_4?s=wireless&ie=UTF8&qid=1513407492&sr=1-4&keywords=moto+x4+case
If you need something more heavy duty though, then definitely get the Tudia Merge. It's a double layer case. I had it but found it too bulky for me. Also the next best case aside from the Spigen and it's a good brand. https://www.amazon.com/dp/B0772T7N6M/ref=twister_B0772W5DWX?_encoding=UTF8&psc=1
I think in your case the Tudia Merge would be best, it's $10.99 as well. These two are the only cases I've found so far from well known brands
+1 for the Spigen