Long story short:
My Humminbird 899si has grown legs and walked away

I currently have 2 - Humminbird 788c's on my boat. 1 at the trolling motor. 1 at the console. (From the factory)
That being said I'm tossing up the idea of what I want to do as far as a new graph at the console.
I am looking to sell the 788c's. And then put a replacement at the trolling motor.
What is everyone's opinions? Would you buy another 899 put it on the console and buy another Humminbird and link the two? Do I switch to Lowrance and get 2 HDS?
What's the easiest thing to do in this situation?
What graph are you running and why? And if you dislike one why do you?