I'm late to the game here. I had collected ALL of the colours myself because I loved it on sight (but have yet to buy...better snap it up! Please vote for red or blue for me!)
Back to you. I rule out the plaid because you said it is summer weight and it is also dark...plus it's a bit muddy/ subdued.
The stripe is gorgeous and fresh. It reads "spring" to me. It also could read a tiny bit "candy-striper." (You might not know what that is, but it is a volunteer position that used to exist for young girls in hospitals...I was one -- we wore pink or blue striped uniforms like this.) However, since you and I have no objection to looking like a tablecloth (Boden dresses, anyone?) I am not sure that should rule it out. It would look wonderful on you.
Red is glorious and you said it is not as blue a red as it appears here (sobbing for myself a bit...but if fire engine, that's okay!). Red can be worn cross seasonally.
In short, I vote both!
In all seriousness, for me it would depend a bit on fabric weight (which I haven't seen) and when you would wear it most. It seems like a good transitional weather dress from the description. Fall/ spring more than deep winter.
You have wardrobe pets to go with both. You have footwear to go with both. Pearls work with both. You're set either way -- you can't go wrong.