What breed of dog best describes the below criteria??

Firstly i would like to say im adopting a puppy from a shelter. However, there are a LOT of litters, with different mixes of breeds, and i would like to find a puppy that would grow into a great dog for me.

ok:

-First a companion, a dog that will always want to be with me, that will WANT to sleep on my bed and lie down with me on my couch (i dont care if you think dogs shouldnt sleep on your bed, every single dog my family have owned had been a shelter pup, and have always slept on my parents bed.)

– a dog that could be a watch dog, but not a guard dog. a dog that would bark when the post man or a stranger comes to the door.

– either medium, medium/large, or large/big (bull mastiff size is the biggest i’l go)

– a dog that will get on well with other dogs (friends and family bring thier dogs to our home all the time) and because i want to buy another puppy when this one is completely trained.

– a dog that will do good with a 20 minute walk in morning, and a 20 minute walk in afternoon, and lots of periods to be outside (for pee, poop and play)

I was thinking a spaniel mix puppy or great dane/corgi mix?? would either of these dogs do well in these conditions?

P.S — i work 6 hours a day, 4-5 days a week, but il have 3 days to have the puppy settle in when i get him/her (and yes, i know this isnt enough time to potty train before you say)
we have an average/large sized yard where i always am, so the dog will be with me running around, plus i will teach him/her to fetch and wel play fetch for 10-20 minutes etc
add: I am aware that puppies need ALOT of time and training, but i do have time. 3 days not going out of the house and leaving the puppy for small amounts of time, and getting him started on potty training sounds fine to me, and can be done. everybody works, and if someone is buying a puppy they cant just quit for the puppy. Its been done before, plus will be checking up on him/her 3 hours after i start my shift.