I would consider getting your feet wet with a Mamiya C series TLR and a Paramender. They are a very cheap, high versatility, and high quality entry into medium format. You get a square picture, and have a bellows. If you like the square format and like to shoot close ups, it is a good option, and will likely give you prints that are for all realistic intents and purposes indiscernible from those shot with a Hassy and a macro lens. If you want something more, move on to a Hassy later, or an RB if you decide that you are not into the 1:1 aspect ratio any more. At any rate, you won't be any more than $300 or so into your C system, and will be able to get that back if you sell it. If you decide to quit medium format after a while, your trials will not have been expensive.
If I had to pick between a Hassy and an RB for a general purpose camera, I would pick the RB, for many reasons, but mainly the larger negative, the aspect ratio, and the bellows...oh yeah: and the prices!
If I wanted something more simple and easily portable (which I do not) I might lean toward the Hassy. Even so, I thought the RB made a decent camera for hikes in the San Gabriels when I borrowed one. Then again, I was evaluating it as an alternative to large format, not to 35 or a Hassy.
Since you are interested in closeups, don't forget that Paramender! Mine is always on in the studio.