LOL at this thread. For every post saying 'get a such-and-such' there is one saying 'don't get a such-and-such, whatever you do!'.
I'd get a rescue dog every time. My old rescue dog dies last November at the age of something over 16 and is very sadly missed by everyone, including the kids. So many people said to me, during the time I had him, 'I'm not really a dog person, but I love Bobby'. Many dogs in rescue shelters are there because of things like divorce, financial problems, moving abroad, old person having to go into a home, etc. They may not have problems at all.
I wouldn't get a dog that needs vast amounts of exercise (such as a border collie) with young children because of the time and energy involved in keeping the dog fit and happy. A dog like a collie NEEDS to work and isn't happy with just a short walk. If you have no sheep for it to herd it needs to be stimulated with obedience or agility classes or some such. Great for teenagers, but not so good for younger ones.
Some cocker spaniels can be a bit schizophrenic and can just 'turn' for no apparent reason (apparently this only affects the solid coloured ones, not the tri-colours). I'd never get a cocker for this reason. The cavaliers are OK, I think, though personally I just find them a bit dull. Retrievers are lovely - have never met a bad one. But don't discount crossbreeds. They get my vote any day and they tend to be healthier too.
We are now looking to get another dog to keep our one remaining dog company (she is pining for her lost pal and whines all day when we're out... ) and we're considering a retired greyhound. They are a bit big, but apparently very very laid back and easy to deal with. Look here .
Good luck.