This is from a personal perspective.
It totally depends on your use. Amex plat is more of a lifestyle card. Unless you use them for your benefits, the annual fee is not justifiable. But as long as you can use the benefits, the annual fee is worth it.
For Reserve, you can actually make use of the annual fee by having enough spends on the card. The annual fee is more justifiable by just the spends on the card.
The added advantage of the Plat card is that you can get annual fee waiver on other Amex cards (I have seen this mentioned at multiple threads, but since I don’t want additional Amex cards, I have not ventured in that area).
I follow a very simple rule. As long as benefits I can get out of the card > annual fees, I keep the card. For me I have enough use cases of having both. So if you are in a same situation as me, why not both? Else go for the one that suits you.