Like a lot of these things, it depends on what you do.
In my experience, there are relatively few cases when you really need them for automotive work, but there are some cases when they make life easier. Other applications, it’s different, and some sort of ball hex can be essential.
I also find that I need short length regular hex bits a lot. In fact I use them primarily. If I didn’t have them I would need ball hex a lot more.
No, the ball hex are not as strong as the regular hex. If you use a hex key with a ball tip the amount of torque you can exert is very limited, but put one of these ball hex sockets on a ratchet and yes, they can be broken. So if feasible, use a regular hex to break loose a fastener then switch.
As to brands, you don’t have the choice in ball hex that you do in regular. I know how easily I can twist regular hex bits, so I really would want ball hex to be good quality.
I don’t own any Bondhus but everything else Bondhus I own is superb, so I’d be happy with those. While I‘m sure they make the hex part, I doubt they make the socket, but they are not usually the weakest part.
My choice would probably be KoKen (regular not Z Series). I find them reasonably strong, they offer regular hex or ball hex in a variety of lengths, and they are not expensive (at least not where I am).
KoKen supply replacement bits inexpensively, so I’d order a set with the sockets.

Second choice would probably be Hazet. I don’t have their ball hex but I rate their regular hex quite highly - they are also tough, and beautifully finished - so I’d be confidant of the ball hex.
Snap On offer these as well. Nice tools, but for me very expensive. The Snap On ball hex are approximately 4 x the price of the Hazet, and they are not 4 x as nice. The sockets are beautifully finished though, and the warranty is worth having in this instance.
