Nail Polish Comparison / OPI vs China Glaze

So for a long time I had been desperately wanting OPI: Uh Oh Roll Down the Window,
one day I spied China Glaze: Westside Warrior going cheap and thought I'd give that a go as a good alternative.

It seemed to be a close enough colour and managed to tide over my Uh oh Roll Down the Wiindow craving.

Now I own both! 
I spied OPI going cheap and that was the first on my list so I bought it!

Now I can really compare the two.

OPI: Uh-Oh Roll Down the Window 
First of all we have all heard of OPI. We know it is a top notch trust-worthy brand, and usually rather expensive (well here in NZ).
This is no exception.
The formula is nice and opaque with a good smooth consistency. I have had this bottle sitting around for a few months now and the formula was still smooth and easy to spread on my nail.

China Glaze: Westside Warrior
China Glaze may not be a brand too many of you know. Prior to my serious nail polish days I definitely had not seen it around (mind you there's not a lot in Palmy, NZ)
I have grown to love China Glaze and have relied on it as one of my go to trust worthy brands.
This formula does not let me down!
I have had this bottle for a while and I did notice, prior to shaking it up for today's post, that there was some apparent separation going on, just a slightly dark film across the top, perhaps about a 2mm line of dark green above the rest of the polish formula. 
A good shake sorted this out, and it definitely was not the crusty film you get from some polishes left over time.

side by side
As you can already see there is a colour difference. While it is not major, side by side it is most certainly see the difference in colour.
The OPI is slightly lighter and the China Glaze a bit darker and more khaki.

both formula's were great!
very opaque, full coverage in two coats

below are photos in different lighting to hopefully give you a fair idea of the colour.
on plastic swatching sticks with no top-coat.

So we can see there is a difference in the colours. The China Glaze is probably cheaper to add to your collection, but go with the colour you like most! 
I think it's highly unlikely you will need both polishes in your collection, but hey, I can't talk - I do have both...

What do you think?
I'd love to hear which one you would choose...