I have both the Blue Cash Preferred from American Express and the Chase Sapphire Preferred cards. I have to say, in my experience so far that they're both awesome cards.
The $75 fee on the Amex is easily recovered in almost no time. I use it most at Giant Eagle, especially when buying gift cards; Think Christmas time or large Amazon purchases! I calculated it out a while ago that the total I received in benefits from the whole shenanigan between the 6% statement credit for using the Amex at Giant Eagle plus the FuelPerks and it was around 12% off the purchase price of the item. Of course, that was before they changed the gift card program, so now it's lower. I bought $3k worth of Lowes gift cards when I replaced my washer and dryer and a few power tools - and had free fuel for quite some time! I did the same when I bought our new TV and Receiver for the theater.
The Sapphire card's First Fridays deal is awesome if you're a restaurant goer. We dine out a lot - I eat lunch out nearly every day at work (it's a social thing, I swear!). But on First Fridays we treat ourselves out to a fancy date night! 3x points at a high end restaurant really racks up (your balance and your point balance! lol). The Chase card is actually easier to use - it's perplexing how few places take Amex. The only thing that's annoying is if you have a second card with Chase, they both have the same card number. There's no way to tell who paid for what like with the Amex, which gives additional cardmembers completely different card numbers.
I always try to use the Amex for groceries and gas (6% and 3% back respectively), but the Chase for food and anything else. Online I always default to Amex, as I feel their security is top notch / better than Chase.
You should check out
http://thepointsguy.com/ - it's a great tool for comparing card rewards.
And finally, my biggest pet peeve: People who don't understand credit will tell you not to use it. They'll never see the 800+ club. If you use it responsibly, you'll be rewarded for it. Screw it up, and you'll be punished. To get to 800+, you should have at least 3 revolving lines (according to sources on the internet) in your mix of credit lines. I didn't break 800 until a few months after opening my Chase Sapphire Preferred. My score dipped initially from the new line and hard pull, but has since rebounded higher than before - likely because of the lower utilization from having more available credit.
Anyway, enough ranting, eh? Which card are you leaning toward?