I agree with Dan that ALL the aftermarket replacements are low quality. That said, when I repaired Kitty's Escape when she hit the deer, I used the Dorman replacements and they work well. Just as good as the factory lights, IMO.
Those last three letters (IMO) are the problem. The difficulty is, what we feel like we're seeing isn't what we're actually seeing. The human visual system is a lousy judge of how well it's doing. It's not just you, it's everyone; we humans are just not well equipped to accurately evaluate how well or poorly we can see (or how well a headlamp works). Our subjective impressions tend to be very far out of line with objective, real measurements of how well we can (or can't) see. So it's very easy to have a situation where we feel like our headlamps are useless but in fact they're doing an adequate job of keeping us safe, or where we feel like we have good (or adequate, or just as good as original, etc) seeing when in fact we don't.
This is why headlamp technical standards are in objective, measurable terms, not subjective terms that have a tester look at the beam and say "Yep, looks OK to me". A very large range of performance is allowed in a legal headlamp, though -- unfortunately there's a lot of room in the standard for mediocre headlamps -- so even on the occasion that the knockoff headlamps actually do meet the standards, that doesn't make them equal to the originals.