I've always had dogs growing up, and have owned a selection of large and small ones. Right now I have a lab/golden retriever mix and a shi tzu.
Personally, I think the bigger the dog, the better.
The bigger dogs seem to be much friendlier and more willing to please. Little dogs can be quite snappy and snarky, I find, and would rather just do their own thing.
There are acceptions, of course, but given the choice, I'd pick a labradore or german shepherd over a chihuahua or toy poodle any day.