I like the EF better than the Frenchi. I feel like the Frenchi is a little too stark in design for your usual style; the points at the bottom of the vest seem too "heavy" and overwhelming and seem to take over the outfit.
Of the three EF sizes, I would have picked SP. At first I was going to say XS, but then I realized that the armholes are a little bigger on that one so that more of the dress shows through. Do you have a preference for how big the armholes are?
I guess I don't know what to say about whether you should keep or not. It sounds to me a bit like you maybe have sales goggles on and are excited about getting a deal but really don't feel it in your heart? I agree, though, that it can be really hard at the end of a season, because the weather is changing and we are already thinking about the upcoming fall palette. Perhaps hold on to whichever EF one you like best and hang it in your closet and see how you feel periodically about it until you get close to the return window?
Having said that, I will say that since I have stopped buying things that were only so-so and that I didn't want to wear out of the store, I have been much happier, even though that means my purchases are few and far between. It was hard at first, as I was a bit addicted to shopping, but it is now much easier, and I am much happier with what I do buy because it is exactly what I want and seems more special since there's not such an influx of new items.