I wrote the BX500 ils easier to find than the MX500, not that it is better. Obviously the BX is worse than the MX, having no SLC cache.
Just that I would not really compare the two. The BX500 is the only Crucial SSD I've ever had troubles with and kinda eroded my trust in the brand. My >10 years old M4 is still working like a champ, so does my MX200.
DRAM-less SSDs are a plague that is very hard to avoid, as it's never mentioned in the spec sheets.