Ymq B2B & Wholesale Solution

This plugin offers premium features at, well, no cost at all. The developers are amazing, they are very easy to reach and work with.
The plugin works flawlessly. You can create tiers for wholesale, you can event limit the purchase quantity which is very handful for us.

The plugin is overall the best plugin for wholesale. I tried several plugins (including premium plugins) and they all had non-straightforward implementation, some simply added a table to the product page with different pricing.