Allies for Daemonhunters

Been playing around with army builder and I can't decide which way to go?
Do I take an Inquisitor Lord and allied Space Marines, or Grey Knights with Inducted Imperial Guard? Would like some help weighing out the pros and cons of each.

So far I am leaning toward the latter. The Inquisitorial Stormtroopers are just to expensive to take when I can take Inducted Guard.
I am also looking forward to trying out the Orbital Blast.

I generally see people taking inducted guard to save on points.

I've never seen/played the other, so I can't really give a lot of feedback.

Grey Knights are so expensive that you usually see people taking a few unit of Guard from the IG codex to add more units on the cheap.

I am not real familiar with the Daemonhunters codex but can you even take Grey Knights as allies in a Space Marine army? I know you can take the inquisitorial units but I am not sure on the actual Grey Knights. I am pretty sure that if you have Grey Knights in a Daemonhunters force you can not take allied Space Marines, only Guard or Sisters.

If I use Space Marines, I have to lead my army with an Inquisitor and take two 5 man stormtrooper units. Basically you cannot have Grey Knights in power armor in the same force as allied Space Marines.