Aside from the obvious choices of a "Labrador Retriever" or a "Golden Retriever" we are more interested in dogs that resemble those characteristics but are a little more original.
Yet, a reliable dog of either of those breeds would be the best choice for your situation.
No offense, but right now your breed choice motivations are a little suspect. Are you
truly looking for a dog to fit your household and lifestyle? Or more interested in making a "statement" to be original or different from the crowd? Don't answer that question to me ... ask
yourself and please be absolutely honest with yourself. If you must be "original", consider a Flat-coated Retriever or Gordon Setter.
The guardian breeds are really bad choices for your situation. With constant comings-and-goings of 20 different guys and all their friends and girlfriends, you absolutely
must have a dog capable of being a total social butterfly. Many people means many more opportunities for somebody to make a mistake ... and forget to restrain a dog that does not like a lot of people (including all your friends) coming in all the time. You sure do
not want an incident where the dog attacks because it thinks it's defending your home, when it's really only one of your friends or a new girlfriend that the dog has never met. You would absolutely be held legally responsible, saying "But we didn't mean it, it was a mistake!" would not get you off the hook. There would be a big fine to pay and the dog would be ordered put to sleep.
The giant breeds are very bad choices as well, for reasons others already stated. But especially because of the giant vet bills that come with them. You might think "Well that's only if some really bad disease happens" ... but that's not reality. Giant breeds require much higher dosages of everything, higher dosages cost much more. This includes routine things like vaccinations and heartworm prevention. Also much higher dosages for problems that are not serious but pretty common, such as minor ear infections or an infected scratch. Injuries can happen
very easily in giant breeds from slipping on floors. It costs very big bucks to x-ray them and treat the injury.
You said none of you are planning to assume any responsibility for vet bills, your parents have agreed to pay instead. From how you explained it sounds like it will not be all the parents pooling money, just your own two parents paying everything. That's awfully nice of them, but do you really think it would be fair to saddle them with a giant breed's vet bills? What if they backed out from sheer sticker-shock, and wanted you guys to at least pay some portion yourselves? Do you guys have a viable back-up plan? Like maybe all 20 of you pooling some of your collective spending money into a special no-touch account just for dog expenses?
Good idea for ya'll to start a "dog fund" of your own before getting any dog. There's
so many expenses, lots more than many people imagine. Who is going to pay for dog's food, collars, leashes, crate, toys, dog bedding, combs and brushes for routine grooming, safe tools for nail trimming, anti-flea or anti-tick supplies, etc.? Your parents? Relying on others to pay for everything is pretty ripe for conflict. What if you need or even just want something for the dog ... and your parents don't agree? What if they only want to pay for the less expensive Brand P dog food, while you know the more expensive Brand I is a much better food?