I don't have an EC9s, but I've had a Shield for about 3 years. For $100 more, I'd probably still take the Shield. The Shield is a smidge bigger and heavier, but mine has run like a champ. Flawless function, as accurate as can be expected in my hands, and carries very easily. IMHO, it also handles recoil like a bigger gun.
With that said, my daily attire is also such that I can pretty much belt carry anything I want. A suit or a blazer most days. If I were planning to pocket carry, I might well go with the EC9s for that $100.