Both are very worthwhile, IMO, for different reasons. I like what I’m seeing in BG3 for sheer graphical beauty, and the latest update with the Druid class also has large numbers of tweaks to small things that are making it better and better.
it does not beat Solasta for the sheer experience of Tabletop D&D in electronic form, faithfully adhering to the game as closely as the OGL can allow. I do find Solasta’s replacement classes for official content to be lacking though in comparison to the stock classes - I really miss my Battlemaster and vengeance Paladins.

it feels as though they played it too safe with the substitute classes for power and balance levels, and their mountaineer, shadow rogue, and nature wizards are coming off as too underpowered compared to the original aubclasses.
However, it’s storyline so far has been very engaging and I can’t wait to see more. I have not played through any of the 5th or 6th level content yet, though, and I hear theres even another upcoming update that takes it to 8th level, so maybe they’ve addressed some of my character class concerns.