A machine doesn't have to be the heaviest in its class to be well-made. The F5 is extra big and heavy because it was meant for folks like traveling photojournalists and sports photographers who were rough on their gear and needed plenty of speed and power, both in the mechanical and electrical sense. If you're mostly going to be shooting static subjects in your local urban environs, then the F5 is going to be more durability and batteries than your needs strictly require. Nothing wrong with using one for such things of course, but if any part of you can be discouraged by the weight of your gear, lighter options are worth looking at.
I shoot medium format and while it's pretty kick-ass, I will take a contrary viewpoint to other posters and gently suggest you don't try to jump right into it as your freshman film experience. While it's no more difficult to actually shoot medium format cameras than 35mm, there's a host of practical considerations which most neophyte film shooters would be happier to be free from while they get their feet wet.
With a 35mm camera, you're dealing with the film format that's synonymous with film in the public mind. A shop that sells film with sell 35mm, a shop that processes film with process 35mm and the film comes in tidy, hardshelled cassettes that are easy to handle. You can talk about "film" and people will assume the majority of the time that you mean 35mm.
When you get into medium format, you're dealing with a completely different film product, the 120 format roll film. It's much less common in retail channels, most frequently only available from pro/specialty shops, costs much more per frame, and processing service is also much harder to find. If you're searching for sales and service related to medium format, you must be specific about what format you're talking about. Just saying "film" when you actually mean "medium format film" is going to net you a lot of disappointments. Also, 120 film is more fiddly simply to handle. It doesn't come in a hard shell cassette, but rather wound openly around a plastic spool with black backing paper to protect it from light. If you're not careful handling it at the start and finish, it's possible for the roll to loosen and get exposed to light as its safety relies upon remaining tightly wound and being taped.
I recommend sticking with your current plan and starting in 35mm. It's the king of convenience in film. You can always move up to a medium format camera later.