You have been rightly advised most large breeds adapt well to apartments, as long as they are provided daily exercise and a run outside in a secured park etc. If you are will to provide atleast 1 hrs walk and exercise twice a day you can go for a gsd, lab or golden.
They all have their own characteristics and requirements for example gsd and golden will require regular brushing as they have longer hair/ coat where as the lab less, but the basic taking care of brushing walking, exercise, good food, etc will be required for all these dogs.
Again it is not advisable to rush into things or do impulse buying as its a long commitments and as advised earlier on in this website calmly think abt the responsibility and only then go ahead.
PS: dogs do not like to be left alone and can get destructive and or if locked up can get very ferocious and aggressive even with owners. As suggested earlier try getting a friends dog and keep it for atleast 10 days to see if u r upto it for keeping a dog of ur own, plus puppies need for time and care.