Personally I would like to see 4 magazines.
Dragon: THE 3e Dungeons & Dragons magazine! But cut out the "book of the month" aspect of wasting an issue just pushing a new book down our throats. I wouldn't mind seeing an Epic Handbook issue a month or two AFTER I have the book to fix any mistakes and add too the setting, but a month before the book comes out, most of what is in the issue doesn't make any sense without the rules.
Dungeon: THE Adventure magazine. Not just D&D, a little d20 and other settings would be OK; Rokugan, Kalamar, or Ravenloft. Also, add-ons and fillers are good. Side trecks, NPCs, Maps of Mystery, or a single Inn, Shop or Town would be good.
Polyhedron: The d20 magazine. They need to get Poly out of the Dungeon (quite literally) and focus on settings other than D&D fantasy. The Shanara issue of Dragon should have been here, as could any one shot book-based settings. With a full issue to fill the Spelljammer issue could have included Neogi, Giff and everything missing from 2e spelljammer and this issue's Omega World could have been expanded to include Featherheads and Botanicals as Races, More Mutations and especially more mutant beasts.
(At least being d20 means I can combine Omega World and Darwin's World almost seamlessly)
The Fourth book I would like to see would focus on 3e conversions. I read once that Dragon tries to avoid converting too much from previous edditions and focus on new stuff, but for those of us with bookshelves full of 1e & 2e, a magazine dedicated to conversions would be nice.
A good title would be Renaissance.