There is a simple huge security difference. If someone gets hold of your tap card, they can use it. If someone gets hold of your iPhone or Apple Watch, they can't use it - without your finger. Plain and simple.
I prefer leaving my wallet in my pants pocket, and either (a) use my watch - it's right there on my wrist all the time, or (b) use my iPhone which is always handy in my shirt pocket.
Having used ApplePay since day one in the US and Canada, I can state that I have never had a "fingerprint misread". None. It's a non-issue.
Pre-ApplePay I had a number of tap cards. Now I only have one, infrequently used, non-ApplePay NFC card left.
I know it is not often mentioned but one additional advantage of American Express when merged with Apple Pay and the Amex App is that your iPhone can be notified (push) for each and every charge made regardless of how the charge was made. Recurring payments, online charges, ApplePay charges, literally any charges. It is the best fraud protection bar none.