Upgrade from Spendor BC-1: need ideas

For more than twenty years I have been living with a pair of Spendor BC1's that I love. When I bought them, I lived in NYC, passed via London a few times, and had a lot of time to listen and compare. Looking back, I did well. Starting with zero knowledge of anything, I ended up with a short list consisting of Quad ESL, but no way they would fit in my room, and the BC-1, which I did purchase.

I am beginning to think about a possible "upgrade", under circumstances that are similar as well as different. My apartment still has no room for the Quads! So it has to be a tower like design again. I don't have time or circumstances to easily listen to and compare a large number of good speakers. That's why I turn to you for advice. If you know BC-1's or similar sounding models (KEF, Rogers, B&W, etc), please suggest specific models that would constitute a meaningful upgrade now,

A few words of clarification:

1. I mainly listen to classical music, but then everything from symphonies to solo flute or vocal. I am not trying to duplicate the concert hall acoustics in my room because I know that is impossible and even good halls sound different anyway. I don't know most singers and musicians personally and don't know what they or their instruments sound like. In other words, while I want my speakers to be "accurate" in the sense of avoiding obvious distortion, I don't have the "original" reference to judge "accuracy". I know and accept that it is all an illusion, and want the illusion to be as beautiful and convincing as possible. I would be happy if chamber and solo sounded like artists were right there. Such effect is difficult with complex orchestral works but I'll take what I can get.

2. The speakers cannot take up too much floor space. The BC-1's footprint is fine. They could be taller though.

3. My present amp is Audiolab 8000S (60w/ch). The room size is 15'x18' (x12' ceiling). But this could change. Therefore, while the speakers should work well with what I have, they should not be overly fussy.

4. Certain brand names keep coming up. Friends suggest Spendor, Dynaudio, Proac in almost the same breath. However, I am also open to smaller less known brands. If there is an extremely talented person making much better speakers in some small town somewhere, let me know!

5. Please suggest specific models. They need not be current models, I am open to discontinued and used. Please give me an idea what a good used pair might cost though.

My plan is to make a short list and see what I can do about finding a pair to listen to (I am in Chicago area). If there is one outstanding candidate, proverbial head & shoulders above all the rest (as Quad 988 would be if it was 1/2 its size!), then I may buy a pair anyway, listen to them and BC-1's side by side for a few months, and then sell one or the other.

Thank you.