Just go for a publisher that has a track record of typesetting and publishing technical books and reaches a large audience. I made the mistake of signing a contract with a reputable publisher for a rather technical book written in LaTeX without checking how their books look first. As it turns out, they are not accustomed to typesetting math at all. They want to convert the manuscript to Microsoft Word, which is crazy, introduces new errors, and is guaranteed to look bad afterwards. I've checked the few technical books in their catalogue, and they look awful. But it's too late for me to change the publisher now.

So, my advice is send your prospectus only to publishers whose books you like and do a little research first. There are surprisingly many publishers who don't know what they're doing (or, to be fair, have different priorities than you).