I don't know how well this link will come through, but here is a link to the
Fantasy Trip Google Plus page, where I took a picture of a 7 and 14 hex dragon I put together.
For 1.5" hexes, I use a Reaper Bones Fire Dragon for the 7-hex dragon, and a Safari Limited Gold Dragon for the 14-hex. For a 4-hex dragon, I use a pre-painted D&D large dragon with an adapter for the base.
For 1" hexes, I use the Reaper Bones Young Fire Dragon for a 7-hex dragon and a dragon from the Safari Limited "Lair of the Dragons 1" collection for a 4-hex dragon.
I have also used the cardboard heroes dragons. There are some pictures either here (on the miniature size thread) or on the Google Plus page of those comparisons.