Well, we don't know what you want to spend, or what cartridge you want to use, so I will assume that you are looking for a reasonably priced unit that will take the MM input from the stock Goldring that came on the MMF-7.
In that case, I would recommend the Gram Slee phono products, as very good for very low money. If you want to spend a little more, a used Lehmann Black Cube would be about $350. This will allow you to change to a moving coil cartridge if you want to. If you want to spend more than that, you should research the market with the cartridge that you wish to use, in mind. There are many good, expensive phono sections available, and alot depends on the application, when you get to that level.
In that case, I would recommend the Gram Slee phono products, as very good for very low money. If you want to spend a little more, a used Lehmann Black Cube would be about $350. This will allow you to change to a moving coil cartridge if you want to. If you want to spend more than that, you should research the market with the cartridge that you wish to use, in mind. There are many good, expensive phono sections available, and alot depends on the application, when you get to that level.