I can't comment on the B Resort and Spa, as I haven't stayed there since it became that name. I do know that my friend HopperFan does recommend it. I think we both consider the DoubleTree Suites to be the best of the seven Disney Springs Hotels. I'd consider the Holiday Inn Orlando Disney Springs to be my second favorite. But, as I've said, I haven't stayed at the B.
The Hilton Lake Buena Vista is in need of a renovation. Aside from that, I've had some significant service issues when I've stayed with them over the past 3-4 years. I've easily spent 60 nights there over that time frame. I've never once had a perfect stay. In some cases, the problems I've experienced have been significant. For example, I've been woken by groundskeepers using leaf blowers before 7am twice. I also had a broken toilet that took 3 calls and over an hour to get fixed. On multiple occasions, I've had housekeeping ignore the "Do Not Disturb" sign on my door.
At this point, the only time I stay there is when it is dirt cheap. By that I mean less than $110 including the $30 resort fee (plus tax). If the B Resort and Spa is priced similarly, I would it over either the Hilton Lake Buena Vista or the Hilton Buena Vista Palace.