Can't it be both? A few more comments on my experience with both video hosters:
1. I don't think it's that easy to make a video private on vimeo. You can set up that it can only be viewed by your vimeo friends or with a password etc. But youtube offers the ability to just send around a link and no one has to sign up on youtube or put in any password to watch it.
2. The lower third ads on youtube can be shut off if you own all the rights to your video. Of course, if you use other people's music or similar, they can't...
3. I tried to upload a video privately and only send to friends on youtube that included some music I don't own. It got deleted instantly. On vimeo, the checks aren't as strict and you can upload almost anything. Be aware though that this doesn't make it legal!
4. The playback on vimeo does go harder on my CPU for some reason... On youtube (even in 1080p), the CPU barely blinks, but on vimeo my laptop starts to turn up the fans after a while. Interesting to know if you have friends with weaker CPUs...
5. What I don't like about youtube is that once you uploaded a video, you can not replace it with a corrected version. On vimeo, you can still fine tune some things and re-upload your work, with the link staying the same.
So, in general: I think youtube offers a little more flexibility and doesn't cost for 1080p. Vimeo offers better quality (yes, noticeably). I would probably recommend you to try out both (the free version of vimeo first) and see what you like better. You don't lose anything...