What's funny is that the very reasons most folks dislike Boomers are the very reasons I like them. I like that they break in quickly and hold that yummy "broken in tone" forever. I also like that they're stiffer than other companies' strings in comparable gauges. So I don't need a thick string for drop tunings and can have the playability of a lighter gauge without drop-D being "flop-D."
On the other hand, I remember trying out a set of Rotosound RS66LDN nickels about 15 years ago. Incredible slap tone, but took forever to lose their sizzle for my bread-and-butter fingerstyle playing. I know a lot of people would absolutely love that (there are always queries on TalkBass on which strings stay the brightest the longest), but not me. I only change my strings once a year, so I prefer my strings more "broken in."
Nothing bad to say about either string, though. Both are very good at what they do. I also have nothing bad to say about flat, but they're not for me. And I'm of the unpopular opinion of preferring D'Addario's old Prisms over their current ProSteels.
The only strings I can safely say I actively disliked were Ken Smith Compressors and I mentioned that in my previous post. Lousy tone, lousy feel, and they fell apart. Triple threat.