Personally, I like the brussels. they are slightly more independent so when you are at work they don't get as worried. thye have pretty easy going personalities (not nearly as high strung as chi's can be) and they are pretty cute.

I would look into rescues. If you aren't concerned about a dog being purebred, look for small mixed breeds - there are lots of poodle crosses out there that make great pets and if you get one that is still a puppy but older than about 5-6 months the foster family can tell you if it is barker (which small dogs can be) or relatively quiet. This would be helpful for apartment living.