Here's what I'd do ...
I'd send it to both companies and agents at the same time. But I would focus more on calling up agents and requesting they watch your demo reel. But I wouldn't just put scenes on it, I'd put the trailer than the entire movie. Call the agent and say, "Watch the trailer. If you like what you see, watch the film. If you don't like what you see throw it away, but at least watch the trailer and give it a chance." That makes you sound confident but not cocky.
I got that idea from numerous sources. One, Robert Rodriguez did that. Two, i've read that same scenario on a "job seeker" website. Three, working in 3 different newsrooms over the past 3 years, I've seen a bunch of demo reels pass through my three bosses's hands. No news director I ever worked for turned down an offer like that (and there were plenty of them). Did they hire everyone that called with a statement like that? No. But they didn't watch too many tapes that just came in the mail without a phone call from the person.
Just remeber that as an indie, you have to market the movie yourself until you convince someone else to market it for you.