Best Speaker For This Room

We recently moved and I've been entertaining ideas of replacing my speakers, but want to make sure I'm getting ones that will work well with the room they are going in.

The Room
- Floor concrete slab covered with carpet
- 16" X 21" speakers 2.5' out from long wall (bookshelves)
- ceiling is 7.5' for most of the room, but 6.5" over the center of the listening area
- Listening seating is 9.5 from speaker position
- Wall behind listening position is 4' back in the middle and 7' back on the sides

Speakers I've been considering include:
Magnepan 1.7s
Martin Logans
Decware Radials
Or just keeping my Tyler traditional box speakers

Given the room, what are speaker would actually create the best sound stage and imaging?
Who can say what is best?? A speaker, however, that might be a rather cost effective surprise is the Dunlavy Cantata. These speakers are small by Dunlavy standards, but still retain much of the capability that this line is famous for. A nice pair can be had on AudioGon in the 2K range. Dunlavy's don't come up for sale too often because most owners keep them for life!
Not sure I was clear. I'm looking for advice given the room on which type of speaker would work best, planar, electrostatic or traditional.
If it were only that simple.

Before you consider any new speaker you should understand the potential of your current speakers and the room. To optimize they're sound stage follow the manufactures placement directions. Also try a temporary placement of thirds. In your 16' deep room (16 divided by 3 = 5'4") locate the surface of the tweeter exactly 5' 4" from the wall behind the speaker and that same distance from the wall behind the listening position to your ears.

Begin with their tweeters distance apart between 5' and 6' with no toe in. Begin toe in in very small 1/8" increments while listening very carefully to the changes in the sound stage between adjustments.

This method can also be used using the short wall making sure the distance from the side wall does not match the distance to the front wall behind the speakers.

Your short list contains three very different speakers not including your current speakers.

Moving from dynamic to panel speakers is a substantial change and a huge difference compared to the radial you're considering.

I'm not a panel fan. The only panel system I would personally consider is from Sanders Sound Labs and that would be the entire system, amp, pre, and panels.

Since your placement is a close 2.5 feet from the back wall you might consider an open back baffle dynamic speaker such as a Nola.
Assuming that the 6.5" central ceiling height (Duck!) is actually 6.5' (Duck, if you play in the NBA ;-} ), that's your overriding concern, right there. I'd probably try to find something with a tweeter that had limited vertical dispersion like some ribbons, planars, or possibly the Gallo tweeter. Beyond that, the room (again, assuming that 16X21 represents feet) should allow most speakers to work pretty well.

Good Luck,