1. NG - Clear cut above the rest, with top-tier moulds and (especially) printing. Only brand to get rolling gears and aerials 100% correct. Best way I can describe them is "refined;" you can't really appreciate the quality unless you actually have one in hand.
2. AV400 - Smidge below NG. Excellent moulds with more extra details than NG (ex. jeweled beacon lights), but the printing and landing gear aren't as good. Aerials are a tad oversized as well.
3. JC - Decent to excellent moulds, hit-or-miss printing. Cockpit windows are particularly problematic. Aerials are a little oversized and landing gears aren't as crisp as AV400 or NG.
4. GJ - Same quality as JC, but ranked lower because they don’t do Cathay and Singapore. Emirates and modern Western airlines don't interest me at all.
5. PH - Dated moulds, subpar detailing, lots of QC horror stories. Only brand I actively avoid.
Dunno much about AC, I don't own any since classics are mostly outside my criteria. The Tristar's one exception, but there's no reason to look beyond NG for that.