I’ve been using the MX-19 betas an RC for a while, and to be truthful I can’t fully recall MX-18,3 before that. I had no complaints about MX-18.3, I won’t even complain about the “conservative” versions, they all worked for me.
However, I do feel that MX-19 is a little faster, a little smoother, slicker, it has a couple of new MX tools (the MX tools are a good selling point) and of course, newer versions. I’ve seen a couple of people complain about the 4.19 (LTS) Kernel when 5.3 and 5.4 are out. They had latest and greatest kit so maybe they had a point, but 4.19, being LTS, works for me.
I think also with every release (since MX-17 anyway) they are improving the looks, nicer wallpapers and more of them. A good selection of themes. The new Xfce 4.14 is working very nicely, in day to day use I had no problems myself with the 4.12, and 4.14 slips right in and works - a good first move, get the basics right THEN look at adding new fancy stuff (if they are going to do that - can’t think of anything I want anyway).
So, MX-19 betas & RC1 worked just fine, the release continues that. Best of all, there’s the MX Forums and community behind it, I’ve seldom, if ever found a better one.
Sorry, I rambled, but then I’m a fan boy…