MeldaProduction MUnison

There are not many harmonizer plug ins that actually harmonize on their own without a dedicated midi track, in the end only this one and eventide quadravox comes for this price range and I found melda production MUnison to perform better and I liked the interface and features more, so I couldn't pass when thomann made a very good temporary offer!
Antares Harmony engine probably works better, but it's twice the price and you need a Ilok key, putting it out of my range actually.
MUnison can actually bring very nice effects on your tracks, so it's totally worth it in my opinion!