The best in 1/72, is Century Wings. Granted they have a limited range of products, but they are a new company and the detail on their planes is outstanding.
I'm also very impressed with Hobby Master. I have examples in both 1/72, and 1/48. I feel that their F4 Phantom is better than even Corgi's. They also make an F9-F panther in 1/48, that is pretty sweet.
For 1/72, aircraft Century Wings, Corgi, Dragon, Hobby Master are all pretty good bets. I personally don't like IXO brand, and I wasn't real impressed with Witty Wings, of course I was comparing their F14, to Century Wings so there is that.
In the 1/48, scale I only have models from Hobby Master, and Franklin mint right now. When finances permit though I would like some models from Eagle international, Marushin, and Corgi makes some WWI birds in 1/48, that I would like to have.