If you liked the way your old speakers sounded, but just want a bit of an update, maybe you should be looking for something similar to what you had. I know that the current line up of Dynaudios are very nice speakers. I'd also probably stick to stand mounters.
As you said, you cannot provide them with a lot of breathing space and I do believe that speakers in larger cabinets are going to need more breathing space.
Please, also understand that due to my own space constraints, my tastes lean heavily toward stand mount and bookshelf speakers. With that having been said, do not discount the speakers from Dynaudio, Paradigm and Silverline. These are all good sounding speakers, each with its own strengths and weaknesses.
Personally, I stayed with the Silverline Minuets. They are tiny, but with a solid amp (and sometimes help from a sub) they fill my 18X20 something plus room very well.
I had a party for the 4th of July and more than one of my guests asked whether the little Minuets were the only things playing.
What I like the most about the Minuets is that they are very forgiving with regard to placement. Although they do sound the best when properly setup, I have yet to be able to make them sound bad, no matter where I put them.
I do use a sub, some of the time. Bass is pretty rolled off at something around 50hz or so. I think that the best way that I can sum up the performance of the Minuets is that I can and often do listen to music for hours on end and only stop when I have to. Not because I'm tired of listening. They are not in the least fatiguing.
I have them sitting in shelves that are about 18" deep and 3' wide and they sound very good. Bass is still tight without it sounding boxy and I'm actually getting an image that extends beyond the speakers and also has depth.
Of course, my choices in speakers reflect my budget. You have more of a budget than I did when choosing speakers.
I will say that one speaker that I've been wanting to try again has been the KEF LS50. My first experience with them wasn't great, but that may not have been the fault of the speakers.