Bambino have stayed around the same relative price point (adjusted for inflation) for their entire life on the market (they also hold only very limited sales) and has only slowly introduced new products. ABU on the other hand has been very competitive with price and has been innovating throughout their history.
I keep some teddy on hand all the time because they're a nice return to what used to be the only decent ABDL diaper available on the market, but they've definitely lost their edge over time. They're probably fine for the majority of users because their standard line has good capacity and features, and their premium cost line (magnifico and bellissimo) has added features and higher capacity. But if you want everyday high capacity or best value for the capacity, ABU is the way to go. If I had to pick one diaper for daytime and one diaper for overnight for the rest of my life, it'd be Preschool (plastic) and Simple because they're the best rounded for me in those two roles.
Bambino is a bit lacking in the customer service department also. They don't seem to have ever shown their face here, and their email response, while available, isn't quite as responsive and interested in helping.
I'd like to see them stick around though, we do owe them one for making ABDL a bit more mainstream and opening the market - showing the next generation of vendors that there's a market here that wants some attention and will give a good return on participation. Although I think it would have gotten here sooner or later, growth in this market would have been much slower without their help, and a lot of us would be tolerating medical grade diapers instead of ABDL good and premiums today.
It looks like they've just chosen to go with the "slow and steady" approach, and that's fine if the market will allow it. There's not a lot of change needed in this niche, a diaper's a diaper. Yeah we've gotten improved patterns, leak guards, and front/back elastic, but there's not all that much of a demand for innovation here. "Steady as she goes" is probably a perfectly valid long-term strategy here.