I have grown to love how the MY looks in white, particularly in the rear and rear quarters areas. It's just hugs those curves down toward the bumper very well, and the contrast with the dark plastic parts at the bottom of the rear bumper look great. However, there were two deal-breakers for me for white: keeping it clean, and by far, white is the most common color of M3 I see in my area, and there are sooo many M3s that it means I'm constantly seeing white Teslas. (I see a lot of white Model X and Y too, and a few S.)
I've never been a fan of black cars, from either a look or keeping it looking nice perspective, so that was never really on the table for me personally. No offense to any fans, I just find it hides too much of most cars' features, and with the Y, it blends in too much with the plastic trims along the bottom of the vehicle.
Red and Blue (the subjects of this thread!) are definitely striking. The best part of the red for me is that it seems to be the rarest Tesla color in the Vancouver BC area so far as I can tell, so you notice it when you see one. It does suit the car well, but neither my better half nor I are a big fan of red cars (again, no offense).
Blue does look gorgeous on the MY. It stands out very well due to the size and shape of the car, and looks way better on MY than on M3 in my opinion. The main thing that gives me pause is the way the dark glass in the back (and roof) combine with the blue--to me it looks slightly awkward. Blue was a tough one to say no to.
In the end, we ordered (and are waiting on) MSM. We are both fans of silver and grey cars generally (we probably would have gotten silver had it been an option), and grey is usually the best at hiding minor dirt and so on. That, and I also love the way the MY looks in it.
Based purely on looks, my preference is probably:
1) White
2) Blue & MSM tied
3) Red
4) Black
Based on "exclusivity" (which is very difficult with a popular model, sister-model, and only 5 colors to choose from), I would say:
1) Red
2) Blue
3) MSM
4) Black
5) White
Based on upkeep effort, I would say:
1) MSM
2) Blue/Red tied
3) White/Black tied
There's my lengthy $0.02 (Canadian pennies).