I have a charnwood that fits flush into the old fireplace, (not my choice, but if I wanted a burner, it was all that was on offer) some remodeling of the aperture was needed. I've had it nearly twenty years, fitted by the housing association, so cost me nothing, although those that opted for electric fires got a £700 kick back. Mine is multifuel, which I find is very useful if I run out of one fuel, I can use the other.
Due to it fitting flush, a kettle or pan to cook on top isn't possible. The only drawback.
I get the chimney cleaned yearly, and it realy heats the place nicely.
If I was going to fit my own choice of stove, it would be a) multifuel, b) one I could stick a pan or kettle on top.
You need to make sure it has the right kilowatt rating for the room size, so some calculations needed there.
I'd also go for something that has the ability to reburn any gasses which I think is called eeco flow, or something like that. Sorry its late, and I'm tired, can't think, but I'm sure someone else knows what I mean.
Nothing like a raeburn or aga in the kitchen though, I have had many evenings snuggled up in an armchair in the kitchen next to a raeburn. Modern galley kitchens are stupid! No room to swing a cat. We lived in the kitchen! I miss it. Radio in the background, sat at the big kitchen table crafting a rug or something, or sat in the armchair, reading or knitting jack russel at my feet, ....... ah those cosy memories!