10 years from now, which will be perceived as the bigger threat to US, Russa or Islamic terrorism

Which is John McCain?

And conservatives were against the Russians before they were for them. It’s almost like this is all a game and doesn’t matter.

A RINO, at least on right-wing sites.

While the OP acknowleges that there is nuance to a situation like this, it ultimately is trying to force a bifurcation where there is no need to, and where it can only mislead.

What is the bigger threat: an extremely unlikely event that could kill millions or a very likely threat that will kill hundreds? What is “more” in the public consciousness: something lots of people think about a little, or something a smaller set of people are intensely worried about?
What is the point in trying to play top trumps?

Also, as a nitpick, I don’t like Islamic terrorism being called the “boogieman”. That term implies a false or imaginary threat, not merely an exaggerated one.
It’s not an imaginary threat.