It's important to realize that even with something as 'generic' as a dog, there is much variation between breeds. Some breeds like the Bichon tend to be very needy and don't like being alone for extended periods of time.
NO dog likes being alone for long, they are pack animals after all; some just put up with it better than others. Generally, smaller breeds tend to be needier and more annoying. The best ones are working or sporting breeds, beagles are the best smaller breed, though I generally prefer retrievers. Avoid breeds that have been overbred as show dogs - the American cocker spaniel was ruined by this in the 70s and 80s and still hasn't recovered, though the British cocker is still good.
