I have played most Pokemon games, but I am deciding between Pokemon Sun/Moon/Ultra and Brilliant Diamond.
I have never played either of these games not even their original versions. What do you think?
Additionally, is Sun/Moon good or is the Ultra version better?
BDSP are 1:1 Unity remakes of diamond and pearl, for better or worse. Platinum just had some small quality of life upgrades and both the legendaries.
Also, BDSP aren't made by Pokemon Company, I enjoyed the games but artistically it's just not Pokemon. If you told me BDSP was a fan game, I'd believe you. It's cool to see a 3d chibi take of Pokemon but I love the art direction of the DS games far more.
Platinum had a lot more than small upgrades, it's just easy to forget how much of gen 4 comes from platinum.