Other than the issue of cosmetic filters (which I don't personally use), the main difference is that for uBlock you can subscribe to really good lists, collected and curated by a lot of people - so it is "defauly allow, except for these...", whereas uMatrix is "default deny, except for what you explicitly allowed".
I run both, occasionally have to allow something in uMatrix, never have to turn uBlock off.
Upvoted for the info, but I'll restate why I use both:
uBlock is my blacklist. uMatix is my whitelist. For various reasons, I occasionally need to skip the whitelist, but I never had a reason to turn off the blacklist in a few years of using uBlock.
Other than the issue of cosmetic filters (which I don't personally use), the main difference is that for uBlock you can subscribe to really good lists, collected and curated by a lot of people - so it is "defauly allow, except for these...", whereas uMatrix is "default deny, except for what you explicitly allowed".
I run both, occasionally have to allow something in uMatrix, never have to turn uBlock off.