Want a more in-depth comparison? Let's break it down a bit more.
Amex Platinum Card vs. Amex Delta SkyMiles Reserve annual fee
When it comes to brass tacks, the Delta SkyMiles® Reserve American Express Card (see rates and fees) is a little bit less expensive than The Platinum Card® from American Express (see rates and fees): $695 vs. $650. So, it's down to how easy it is to make back that fee in perks and credits.
The Platinum Card® from American Express claims you can get "over $1,500 in Platinum Value." While I don't think the typical cardholder is maximizing to that extent, it's generally not very hard to get at least your annual fee's worth, if not a bit more. For instance, if you use up the Uber, streaming, hotel, and airline fee credits each year, you're getting $840 in value from just a handful of the potential credits. Terms apply.
On the other hand, the Delta SkyMiles® Reserve American Express Card's companion pass could net you that $1,500 in value (or more) on its own when redeemed for, say, a roundtrip first class domestic ticket. Terms apply. Whether you can do it organically is the question. How often do you already fly Delta first class? If the answer is "never," then this isn't as valuable as it seems.
Winner: Tie
Amex Platinum Card vs. Amex Delta SkyMiles Reserve welcome offer
The specific welcome offer you get from Amex can vary based on a lot of factors, like your browser or whether you have a referral. But in this case, it's not about the size of the bonus; it's about the currency.
Most of us are trying to turn travel card welcome bonuses into free flights. This is way easier to do with a flexible currency, like the Membership Rewards you earn from The Platinum Card® from American Express's standard welcome bonus. Earn 80,000 Membership Rewards® Points after you spend $8,000 on eligible purchases on your new Card in your first 6 months of Card Membership. Terms apply. These are transferable points that you can transfer to more than a dozen airline and hotel programs. You can also redeem for travel through Amex Travel.
The Delta SkyMiles® Reserve American Express Card earns 60,000 Delta SkyMiles that are deposited directly into your SkyMiles account after spending $5,000 in the first 6 months. Terms apply. You can only use them for Delta purchases, so you're severely limited in redemption options.
Unless I'm specifically trying to increase my Delta miles, I'd rather earn 80,000 Membership Rewards® Points Membership Rewards than 60,000 Delta SkyMiles.
Winner: The Platinum Card® from American Express
Amex Platinum Card vs. Amex Delta SkyMiles Reserve intro APR
Neither card offers any kind of intro APR deal, so everyone loses here.
Winner: Nobody
Amex Platinum Card vs. Amex Delta SkyMiles Reserve rewards
I have to start by saying that neither of these Amex cards are ones you're getting specifically for the purchase rewards. These are cards you get for the perks and benefits.
With that out of the way, purchase rewards are another place where The Platinum Card® from American Express is an easy winner. Indeed, I'd argue it's even the winner for Delta purchases. You earn 5X points per $1 on flights booked directly with the airline, which would include Delta flights purchased through Delta. Terms apply.
In contrast, the Delta SkyMiles® Reserve American Express Card only earns 3X SkyMiles per $1 on Delta purchases. Terms apply. SkyMiles vs. Membership Rewards argument aside (but, you know), 5X is more than 3X.
Winner: The Platinum Card® from American Express