I personally think the NFB-12 is an excellent choice for a budget amp/DAC, but then again, it's the only unit of the sort I have ever heard. Very few people have actually compared multiple budget amp/DAC's as far as I know. I do know Brooko choose the NFB-12 over the FiiO E7+E9, so it can't be all that bad. Furthermore, the NFB-12 is fairly neutral and has plenty of power, so it should be pretty future proof too.
I think in the budget range for peoples first buys, they should just go for equipment that is highly touted and don't worry too much beyond that. Just make sure it doesn't have synergy problems with the headphones you plan to get. With low end equipment, that's usually never a problem.