I love Cockers. Just make sure you read up on them. I personally would take the cocker, because they work well if you take care of them.
Just go to the WGP forum and check the stickies. The CF tank and the E Bladed cocker are going to be better then a steel tank and a mini. But if you want a good gun that is cheap, check out the DP Fusion. It's $350 and people love it.
I'd still take the cocker, though.