Viroflay is an excellent spinach, especially for cooking.

It's sweeter than a lot of heirlooms, even when stressed. Warm climate winter growers love it because it has less of a chance of going bitter/strong during occasional high-heat events.

I've had friends grow it. The only knock from some of them is that while it's sweet and rather tender it can be a bit a thick (though still tender) if picked in the "baby" stage...but that's a positive to some and doesn't matter to those that grow it for cooking.