Sweet Watermelon is their brighter candy version.

Double is a deeper watermelon that is more natural and stronger in terms of % needed.

Mixing both would be okay. I would do 2:1 / Sweet:Double

Never tried the Double.

I can, however, say that FA Red Summer (Watermelon) is a nice take on the fruit. Less "candy", more fruit-focused. Jungle Flavors also makes a nice candy-ish Watermelon, though very new. Still experimenting.

For a lot of folks who LOVE watermelon vapes, Lorann seems to be the perennial favorite. It's OK. Still always preferred Flavour Art's version, although lacking sweetness of the Capella. No one compounder makes the "perfect" watermelon. Like pineapple, you may have to go with a 2 or 3 flavor mix.

The cap double watermelon is almost the watermelon jolly rancher flavor. Just classic candy-ish watermelon. I mix it by itself or with others and I like it.

It depends on what you're looking for in a watermelon. Do you want a candy watermelon or a more natural one?

I'm partial to CAP Double Watermelon, over CAP Sweet Watermelon at least. I find it in ways very similar to LA Watermelon, which is my go-to when it comes to most of my uses for watermelon, ie. candy applications.

Double Watermelon tastes more authentic that Sweet Watermelon, which just tastes like Jollyranchers to me. While I like both flavors, I definitely prefer Double Watermelon as it's a little more complex and doesn't have the harshness some fake watermelon flavors have. (Wild Melon by Flavorah is also amazing... FYI)

I personally prefer Sweet over double. The double is too "Dark" of a flavor for me and a bit rindy. I like the candy type flavors though. My favorite Watermelon is LorAnns (Clear).