I was looking for BIG inserts. Here is my short list:
Osburn 2400 (good size firebox, not catalytic, lots of very satisfied users on hearth.com, firebox will take 21")
Kuma Sequoia (take 8" liner)
Buck 91 (takes 8" liner)
Buck 94NC (takes 8" liner)
Blaze king KING (takes 8" liner)
Regency I3100 (although I have read too many bad things about their customer service)
Quadrafire 5100i (puts out a lot of heat for it's size, pretty advanced combustion controls, not catalytic)
Hearthstone Clydesdale (pricier, but hearthstone doesn't make junk either)
These two are no name inserts that I stumbled across in my search:
http://www.woodlanddirect.com/Firep...ytic-Wood-Stove-Insert-with-Original-Surround
http://www.fireplacex.com/productguide/productdetail.aspx?modelsku=99800604
I have ultimately decided to go with a free standing stove, but hopefully this helps you.
I started with a list of about 60, and these are the only ones I was still considering.