I am team Amex and Chase. I have an Amex trifecta of the Platinum, Gold and Green. I have the Chase trifecta of the Sapphire Reserve, Freedom Flex and Freedom Unlimited. For domestic economy travel Chase is easier to use with better transfer partners such as United, Southwest for airlines and Hyatt and Marriott for hotels. The benefit of the Sapphire Reserve is when you book flights in the Chase portal you get a 1.5x boost on your points. Combine that with the points earned on that card you can combine points from the Flex that gets a rotating 5x category per quarter and the Unlimited for 1.5x for non boosted purchases. The Reserve does have a hefty annual fee of $550, but it comes with a $300 yearly travel credit, Priority Pass Lounge access and Chase has started to build there own lounges to compete with the Amex Centurion lounges. The Sapphire Reserve and Preferred also offer primary rental car insurance which Amex doesn't.
Amex is learning how to transfer out to partners. You need to be flexible with dates and do some legwork. IF you fly international business and first class that is the sweet spot for outsized value. Domestic travel is meh. The Platinum gets access to the Centurion lounges along with Delta Sky Club when on Delta flights. If you travel through airports frequently these are a nice perk. To offset the annual fee of $695 for the Platinum you get many credits including monthly Uber, airline incidental credits, Fine Hotels credit, Digital credit such as Disney +, Walmart + membership and others. The Platinum is not a good points earner by itself besides flights. It is about the benefits if you use them. Paired with the Gold you can earn points fast. If you have a Schwab brokerage account I would get the Schwab Amex Platinum. Depending on your funds you can get a credit for the annual fee. You can also cash out your points to your Schwab account a 1.1 cents per point.
If you are strictly American Airlines I would look at their cards as they don't have transfer agreements with the big three which is Chase, Amex or Capital One. If you will be flying a lot and be in airports with an Admirals Lounge look at the Executive World Elite. Annual fee is high but you can get you player two an authorized user card for no extra money and get lounge access, TSA Pre Check credit, priority check in and boarding, first bag free for up to 8 companions and more. For a day to day card it only earns 1x. This will be your card for AA purchases and booking travel and hotels through the portal.
My wife is active duty USAF so no annual fees for us and all of the perks. When her career is done we most likely will stay with Chase for the ease of use and transferring points and dump Amex.