Hello Barry
A fundamental principle when dealing with BGP on your network edge is that when you advertise your public IP prefixes to the internet using BGP, you can influence incoming traffic to take a particular route but you don’t have ultimate control.
What this means is that you can try to get the BGP neighbors of your edge routers, specifically, the ISP routers, to prefer one route over another to get to your prefixes. But any such attempt can be overridden by your ISPs. The best course of action is to talk with your ISPs, let them know what you want to do, and coordinate with them on how to achieve it.
Now the attributes that can be used to influence incoming traffic are:
In addition to this, you can also leak more specific routes to one of your ISPs, since BGP prefers more specific routes over less specific routes. But this may be viewed as a “hostile” act by your ISP, so make sure you speak with them first!
I hope this has been helpful!
Laz