You can learn quite a bit about each breed from their AKC Club.

For instance, Cavalier King Charles Spaniels have a lot of genetic defects due to improper breeding (my groomer shows them, she owns 5). Plan on a separate bank account for your vet!

Some are going to need a lot of attention to the coat. Most are going to need obedience classes, although as you go through life and own first one and then another, you will become a good alpha leader. Border Collies need a job, or they will be in trouble constantly, and will try to herd cars.