I plant just about any of my fall crops in the beds my garlic and onions grew in. Some of my favorites to follow garlc are cabbage, broccoli, cauliflower, brussels sprouts, kale, collards, lettuce and spinach. I've occasionally planted fall root crops like carrots, winter storage radishes and turnips but those usually go in my spring lettuce beds after it's all been harvested.
It doesn't hurt to grow a short term cover crop like buckwheat in the bed before transplanting your fall crops. It keeps the soil weed free, makes a natural mulch to transplant into and adds organic matter back to the soil. Just make sure to cut the buckwheat down about the time it's in full bloom if you haven't already cut it and transplanted into it.

Here in zone 7/8 we plant late beans too.

Here in zone 7/8 we plant late beans too.

I have read that buckwheat is good for growing garlic. I am going to give it a whirl this year. I believe cover crops keep the soil in better shape anyway.

I've never used it before garlic. I just use it after an early maturing crop to keep the soil covered until I plant late crops.
I normally practice a crop rotation where I grow legumes the first year, vegetables the second year and a small grain crop like oats or wheat the third year. Then I start the cycle over again. I have never had better production out of a piece of land as when I rotate crops and use cover crops. I also have a lot less disease and insect pressure since I've started using sustainable and organic practices.