Hi hukka, and welcome to CPF!
I am familiar with one of your unknown manufacturers, Kingbright.
I bought several different 3mm Kingbright LEDs from Digikey, and was disappointed. Not nearly as bright as the Avago and Cree 3mm parts I had been buying. Of course, they were less expensive.
Then at work we got some Kingbright 7-segment LEDs for our hand held terminals. These were very good! Brighter than our previous vendor, and not a single defect.
A mixed bag, you might say.
Cheers,
Jeff