Again, I would say it depends on what you're looking for. Do you want something to carry your camping gear, store purchases, laptop briefcase, etc? I used the Bestem 2012 for @57,000 miles. It carried all that, plus things like cases of Costco brand soy milk and their bird seed that probably weighs about 40 lbs. I'm not sure about the weight, but it easily exceeded any limitations by the bike manufacturer for how much weight could be carried there. It did fine and never failed.
Actually, I should correct that statement. The wire strap that holds the lid from falling too far backward when opened did finally give out. But in 57,000 miles of use...that's not bad for an $80 top box.
I've owned two Givi top boxes, and except for the material the top box itself is made of, they are about the same. Good quality, and they hold up to everything I've dished out to them in about 30,000 miles...but I'm not sure there's three times as much value in them for the three times cost.
If you go to the expensive line of Givi products (Monokey), the carrying capacity is technically greater, but it seems like a moot point. (a) If the Bestem 2012 can carry all the weight and abuse I gave it without failing, then the Givi Monolock (less expensive versions) should do fine. And (b) how much weight do you want hanging off the back of your bike and placed up high? You wouldn't want much for any distance, because it would upset the handling a lot.
The Bestem 929 seems to be a clone of the Givi e460N. If the Bestem 929 costs $80 with LED lights, and the Givi e460N costs $245...without lights or a backrest pad...what do I get by buying Givi except the name?
If you're looking for functionality, the Bestem product line is good. If you're looking for something pretty to impress your friends, be prepared to spend several times more.
Chris