PayPal Standard is usually easier to setup and use.
PayPal Standard and Stripe work in a different way: After the appointment booking form submission PayPal Standard redirects the user to a PayPal hosted page where the customer can pay with a PayPal account on credit card. When using PayPal Standard you don’t need SSL at your website since no sensitive payment data is entered in your website, however SSL may be recommended anyway.
On the other when using Stripe a floating panel for entering the credit card payment data is opened directly over the appointment booking form instead making a redirection to a payment page. In this case since the payment information is entered (at least visually) on your website the SSL connection is strongly recommended.
For further information about the features on each version feel free to post a message at:
https://abc.dwbooster.com/contact-us
Thank you!