So first of all, yes, I have been enjoying BDSP so far. Just being able to revisit Sinnoh with modern mechanics is pretty amazing, and while I am somewhat disappointed in the general lack of new features, I think we should probably appreciate that's what separates a remake from a remaster. I wouldn't qualify these games as remakes; I'd say these are remasters, and in that regard I think they're very solid games, especially from a developer with little prior experience developing Pokemon games.
Now for the second and third parts of that question. I think in a vacuum with all other things being equal, yes, I prefer BDSP to the original DP. They're essentially the same game, only with BDSP having updated mechanics and some minor improvements in things like the team quality of various NPCs. However, that comes with the caveat that I think DP were massive steps forward in the Pokemon franchise (in my opinion, the single most important generation) and the gap in progress between them and their predecessors was much bigger than between BDSP and its predecessors.
I would say I enjoyed playing Diamond for the first time more than I enjoyed playing Brilliant Diamond for the first time, not because Diamond is better if you compare them directly to each other, but because it was that much more revolutionary compared to previous entries in the series. I expect I probably had a lot more playtime in DPPt than I will accumulate in BDSP. Of course that isn't a fair comparison, I was much younger and had much more free time and frankly interest in the Pokemon series when the original DP came out, and BDSP isn't exactly supposed to be a revolutionary entry in the Pokemon series; it is, as described, a faithful remake, but while I think BDSP are the better games without considering any other factor, I think DPPt advanced the series much farther than BDSP did.
As for Sw/Sh, I have to take a somewhat weaker version of the same stance. I'd rather play BDSP (at least at the moment), but Sw/Sh did lay some important foundations for the Pokemon series that BDSP simply didn't. That being said, the current trend seems to largely be straying away from traditional Pokemon games in the way that Sw/Sh were, so we'll see how relevant that really is going into the future.
All in all, definitely solid games, but not revolutionary in the way their predecessors were. But then again, that was never the goal.
