Right now, I'm using a Prevue Hendryx Pet Products flight cage. It is awesome for the price! But, like Sarahmoluccan said, there is no perfect cage. The Prevue Pet Products cage I have is good, but parts of the cage are a tad bit flimsy. This hasn't been a problem, as my birds are small Budgies. But it's definitely not the sturdiest cage out there. The food bowls were cheap plastic, and about 3 of the 4 of them broke, but I easily replaced them. It came with 3 perches, but they were dowel perches (which aren't good for birds' feet). The cage wasn't hard nor exactly easy to assemble. Me, my dad, and my brother put it together in about 30-45 minutes. Most Prevue Pet Products bird cages are too small for permanent living. I just happened to find one of the larger ones. I'll just say this, the $100 I spent on it was well spent. However, next time I go cage shopping, I'll try to look for another brand. If you're looking for a good, cheaper cage, the Prevue Hendryx Pet Product flight cage is the way to go. But, if you have the money, I would suggest looking at different brands.
Recently, while just looking on the internet, I came across a Critter Nation cage, a cage meant for rats, hamsters, Chinchillas, etc. But I've got to say, based off all the information I found, it could be a great bird cage! It's got 1/2 bar spacing (good for smaller birds). And the bars are horizontal, which makes it easier for birds to climb. It's got a slide out grate. It's got shelves meant for other critters, but their removable. This is just a small summary on it. I made a post with more information on it. Here it is:
Great Cage for Birds! | Avian Avenue Parrot Forum
The two cages I discussed above are, however, meant for the smaller guys. Birds like finches, Budgies, Cockatiels, and MAYBE even Green Cheek Conure (sorry if I'm wrong on this. I'm not sure exactly what the cage requirements are for these adorable birds). It would be great if you could tell us what bird you have or plan to have, that way we can suggest cages made for birds around the size of your own. I hope the information I provided was helpful!