The special 650 bmws that touratech offer look pretty good similar to the dakar bikes very purposeful.
How about the basic bmw 80 gs thats a cool looking bike no unecesarry styling bits just the bits you need.
The new tenere looks good too.
Look up survival bikes they are a form of rat bike very mad max they look like they would scare the natives.
There is only one problem of having a good looking overland bike and that is that if it looks good and flash someone else is probably going to want to get their sticky mitts on it.
Maybe its better to dress down so to speak, lots of odd colours and gaffa tape help with this.