To a certain extent, it depends on the type of structure you're interested in. If it's brick, you have (IMHO) only 2 choices - Cornerstone and DPM. However, if you want to make your brick structure really unique by pointing the mortar lines, something else that factors in is the color of the plastic. I prefer a brick red color, because all you have to do is point. If you choose a kit that has a light tan background, you'll probably want to paint it first, and that opens up a whole new can of worms.
I use most of the makers that have what I need. DPM, Walhters, Life Like, Bachman, Vollmer, Kirbri, Korber. Did I miss any? Most kits may not be exactly what I want but can be bashed or modified or, used for parts.