As a dog lover, you probably love all dogs. Ask yourself this question: In a crisis, could I ride him? If yes, thats a big dog. However, if you live in Los Angeles or any other big city, apartment living is the only affordable option (unless you are the inventor of kale).
Challenge #1: Your apartment allows all dogs, but there is no backyard.
All in all, this is a pretty manageable challenge. You can make sure your active big dog gets a lot of exercise by taking it to the dog park or on long walks. If you work full-time, there are many dog-walking companies that make it easy to ensure your Marmaduke gets plenty of fresh air. Wag is great! Alternatively, you can get a breed that is less active. Animal Planet suggests a bullmastiff or a clumber spaniel. Check with your vet to make sure your apartment is conducive for your big-dog breed.