I use modo drum alongside BFD3. I’ll say that while some parts of modo drum are really cool, some other parts have a way to go, and I don’t think it could stand alone as my only “realistic” drum sample library. Some things in it are just not there yet like the overhead and room IRs, and the kick drums are great except there’s just a little something barely synthetic (which I happen to like) to the modeled sound.
I also use superior, addictive, mixosaurus and ocean way (along with 2tb more of libraries and samples I’ve gotten over the past 25 years), and to this day nothing sounds more live than BFD. That’s why I’m still here.
As for BFD alternatives I think committing to one software is going to be very rough if you’re a hardcore dedicated BFD user, none can come close to giving you that much since the way BFD is sampled makes it was more flexible than something like Superior which is much more “produced” sounding with a homogenized sound.
BFD is a bit clunky for me to use right now so my alternative is just going into Kontakt (which I hate having to use) and loading up a full Mixosaurus session (best hihats and cymbals ever sampled by a long mile, nothing even today comes close) and layering the kick and snare with Roomsound drums or reinforcing them with Boss DR-660/Akai XR10 samples and it’s a monstrous sound.
I don’t know how popular the sentiment is but I still use samples released 10/15/20 years ago and they still sound great. BFDs XFL and Deluxe stand up to anything modern, so there’s nothing really wrong with looking backwards in time and picking something old. If you don’t mind Kontakt too much there’s nothing wrong with their Studio drummer or the Abbey Road stuff (80s drummer is particularly excellent to my tastes).
Modern samples/libraries (while awesome) are either gimmicky (IK) or a huge commitment (SD3). I have to be versed in and own all this stuff to be able to work with clients on active sessions for arrangement and mixing, but on my personal music rig I only have BFD and Kontakt installed for the above scenario.
**I should be clear that anything I am uncertain about in MODO is inaudible to me in a mix, but the way I mix and arrange I’m so hyperfocused and surgical at times that I can’t help but hear things I might not be supposed to.