I have the AMEX Platinum because I needed a second card and sure it does have it's perks, but I still like my Navy Fed card. In terms of features, the rewards points program with Navy Fed is way better and simpler. I usually return the rewards points for a Visa gift card that I can use on anything I want. The AMEX is kind of a pain and doesn't return points at nearly the same rate as the Navy Fed card. Plus, I've been very happen with my experience with Navy Fed.
I'm not a crazy point chaser, but I have 3 cards for distinctly different reasons:
1. Discover More - this is my main card. The rewards are 1% on everything and 5% back on rotating categories throughout the year, and they are all things that I already spend on (like right now is gas), groceries is an annual one, as are home improvement, and they for the past several years have made online shopping and amazon.com 5% back in the final quarter of the year right when you're doing holiday shopping anyway. I get a considerable amount back and parlay that into a gift card that usually has a 5-20% bonus on top of it to a restaurant or something. I'm ideally saving up for a cruise at this point. The travel protection for insurance is similar to AMEX Platinum.
2. AMEX Platinum: the perks, pretty exclusively. I use occasionally, they do have the nice added in extra warranty for purchases, but haven't had to use it yet. I plan on eventually using the international first class bonus seat here. I have 50,000 + points here, but it's not a great value unless you're trading in for airline miles at a higher than a 1:1 ratio. Using the points for cash (in the form of paying off purchases) is a terrible ratio.
3. NFCU Cash Rewards Card (the green Visa they offer): Simplicity and safety. Visa is literally accepted everywhere. NFCU's website loads on even the slowest, crappiest boat internet and their rewards are a straight 1.5% cashback all the time, which adds up quicker than one might think. Redemption options are not quite as good as the Discover, but redeeming some cash to put in your checking account is super simple.