Best plants to include in companion planting and rotation plan

Hello,
I would like to hear what are the vegetables you find key components of your companion planting and crop rotations plans.

I've been working on a reference tool for applying those techniques among others (http://www.farmingkit.com/) and I want to make sure I include the most popular and useful plants, even if they are non-edible flowers or cover crops.

Thanks in advance!

Howdy Nick welcome to permies!. Looks like a neat idea there. You might want to read through some of these posts for ideas too.

https://permies.com/forums/jforum?module=search&action=search&forum_id=2&search_keywords=companion+planting+&match_type=all&search_in=ALL&forum=2&sort_by=time&sort_dir=DESC&search_date=ALL&member_number=&member_first_name=&member_last_name=&member_match_type=memberPosted