Hello Zouhair
In a network topology where you have employed an FHRP as well as multicast, you will find that multicast traffic will not necessarily conform to the FHRP elected active router. Multicast works independently from the FHRP, so the decision to align the forwarder with the active router should be applied to improve load balancing based upon the expected unicast and multicast traffic patterns.
FHRPs aside, there is no particular advantage of having the same device become the forwarder and the DR so your choice can go either way.
When employing FHRPs with multicast, however, it is useful to employ something called HSRP Aware PIM, for HSRP implementations. This is a feature that allows multicast to become aware of the HSRP topology providing consistent IP multicast forwarding in a redundant network with virtual routing groups enabled. You can find out more about this feature at the following Cisco documentation:
A similar feature is available for VRRP as well.
I hope this has been helpful!
Laz