VO5 conditioners (specifically the fruity ones with that silk stuff in it) and the Suave Naturals specifically Cherry Blossom and Mountain Strawberry are amazing on my hair for some reason. I don't know exactly why but they work better on my hair than the more expensive conditioners that cost like much much more.
I am really stuck on 2 cone free GF conditioners but I keep an ARSENAL of V05 and Suave Natural conditioners under my bathroom sink in the cabinet. TONS OF THEM. It's ridiculous how I have to buy like 3 or 4 every time I go to the darn supermarket of drug store. LOL!
What may be causing your itchy scalp is called Methylchloroisothiazolinone.
It's a preservative found some cosmetic products that are ment to be in contact with the skin for a amount of small time and rinsed off.
It basically has anti-fungal and anti-bacterial properties. It can be a skin irritant for some people and was removed from a lot of cosmetics for that reason except for rinse-off products like certain skin creams and hair products that are meant to be rinsed complete off specifically like conditioners. And Suave AND V05 do indeed contain this ingredient in MANY of their conditioners.
I had the same problem with certain Suave Naturals and VO5's at first because I was using them so much as leave ins because I was so nuts about how nice they made my hair look and feel. I stopped using them as leave ins so much and when I do I am careful to try to not get very much on my scalp. I find using a spray bottle helps me control getting it mostly on my hair instead of my scalp.