choose the one thats suits your hand, they are both great
Ec2a feels better and better build quality
save up a bit more money and buy a g703 and you're pretty much set for the next 3-4 years
Well I'm going to be biased since I've sworn to Logitech since the MX-series. I've had Steelseries and Razer, but i keep going back to Logitech.
Love the G403.
But, yeah. Choosing mouse is totally individual. Everyone have different hands and preferences. If you can, i would go to a store try some.
if the choice is zowie vs something, choose zowie.