Here's some thoughts and things you've probably heard before:
Neve: good and fat, warm and crisp. Vintage with big knobs is best. Expensive and if not maintained prone to breaking down and blowing up. But probably the best. Flying faders very good and now a standard on many custom desks.
EMI: straight through, round, all there. Mil. spec. Eq very smooth and broad. Have to be decisive on 2db steps but easily recallable. Compressors on each channel OK but not that special for me and difficult to control and prone to nasty distortion on sibilance sometimes. Channel input meters very useful. No cut buttons on original cassettes. Beware hum breakthrough earthing problems on echo and foldback sends. Nice track announce button. Dont know so much about Chandler stuff so going on TG1234
API: Mil. spec. Good solid un-enhanced sound. Have to be decisive on 2db steps but easily recallable. Compressors not so good for me. Simple layout and even simpler monitor section on some desks.
Helios: rare but very musical. What's going on with the 60hz even when its turned 0db? Sounds great and always left in for me. Nice hifi top end crispness. Usually Helios desks have been modified or repaired drastically so you find channels all sound a bit different in response. Foldback and aux sends bit small and fiddley.
SSL: well, things always sound different when played through SSL. People say you should record class A discrete and mix SSL and they may be right but I've always got great results making whole record on SSL. Its a tight sound and for mixing excels by being able to fine tune frequencies with eq, use small amounts of channel compression finely tuned and the great G series automation. It may seem primitive but it still does job for me.
Trident: TSM series was great desk and rarely seen now. Beefier than Series 80 with sliding faders for eq, usually in yellow. Always separate monitor section so simple to operate. Many Trident desks had eq on monitor which was always bit dangerous to use as you couldn't reproduce it the same on the main channels so you'd end up mixing on the monitor section. The mini faders on monitor section may also have helped the sound. Great desks. A range suburb
Amek: Angela is cool compact and good sound.
MCI: Excellent. They have MCI at Rockfield and Eastcote.