A small dog is easier in the house. I love big dogs, had bog dogs growing up etc but wish I had got a smaller dog now.
He's mostly right, obviously there are exceptions, terriers need lots of exercise but in general a 30 minute walk with tire a terrier out more than a german shepherd for example.
Bigger dogs cost more, food, vets, some boarding kennels.
When you need to shut a dog away, when cleaning or people round etc, a smaller dog is easier (big dogs can jump gates, open doors)
When you have people round, a big dog is more 'noticeable' and 'in the way'
When a small dog jumps up it is annoying, when a big dog jumps up it can be dangerous!
Lots to consider, and really it depends on the breed and the individual of the dog, but in general, unless you have a huge house, lots of money and unlimited exercise time, a smaller breed is more sensible.
However, lurchers/greyhounds kinda are the exception in terms of exercise and space as they don't need a lot and curl up pretty small.
They will counter surf food though, their noses are always the exact height of the counter.