No sure what exactly you mean by "off-brand", but I have recently bought big sets from Mould King and Cada and they are perfectly fine. Not only are they cheap,

No sure what exactly you mean by "off-brand", but I have recently bought big sets from Mould King and Cada and they are perfectly fine. Not only are they cheap, I'd say the color consistency is even a bit better. The sets themselves are great, really creative, challenging to build even for older kids, something Lego stopped doing many years ago.