Their points are becoming worthless (Chase has done well in this regard, partnering with United and Southwest), travel booked directly with Amex is usually simple more expensive than other travel aggregators, Costco is dropping taking Amex, etc.
I signed up for a Chase Sapphire Preferred card, and its far superior. Its rental car insurance is first tier/full coverage; I have no need to file a claim with my own insurance ever if I use the card. The rewards are much better, and the yearly fee is only $100.