I have an Mcusta Kasumi and a Kershaw Nakamura.
Like Tim says, I think it really just comes down to asthetics.
They are both very sharp and have VG-10 cores. They both have solid lock-up with no play. They are both delicate and small, but not fragile. They are working gent knives, not display pieces. And they both have typical fit and finish for the price range.
They are ergonomically similar and damn near the same size.
So go with which you think looks better, or you are drawn to more.
Keep in mind that many Mcustas do not have a pocket clip, in case that is an issue for you.