Multipath Rules vs Static Routing (Policy Routes) ?

Dear Experts,

We have 3x Internet access lines using Uplink Balancing.

We are using services for online file storage accessed by WebDAV (HTTPS) mostly.

I want do force all the traffic on HTTPS to destination i.e. "PROVIDER.com" to go over our dedicated line (same upload and download), let's call it "line1".

What is the best strategy in performance regarding the Astaro overload? And what is the difference in between?:

a) using Interfaces&Routing > Static Routing > Policy Rules (Any>Any>HTTPS>provider.com>interface "line1")

or

b) using Interfaces&Routing > Interfaces > Multipath Rules (Any>HTTPS>provider.com>line1)

Thank you in advance!
Uwe