Facebook and Twitter are completely different platforms, so it's not a straightforward answer. Facebook has way more users, but it's hard to find those first followers. You're really only visible to your followers, and to people who see them liking your posts. With Twitter it's easier to get in front of new people (live streams, trending topics, giving people shout outs and retweets, etc.). But people care much less about any single tweet.
So in the short run, maybe twitter, and in the long run, facebook. But even that depends on what kind of supplemental content you're most capable of producing.....
Full disclosure: I hate social media. I have a Twitter account... I don't tweet. I'm on FB, because I use it to advertise, that's almost entirely it, but I post a few things, like milestones or what have you, and interact with reader comments which is the other key. The only reason I'm on either is writing.
But what do you mean by raise awareness? I'm a believer in the writing and story raising awareness, that's how you know the people following you are your target audience (or at least it's a solid lead). I think a lot of writers spend a lot of time building a social presence stuffed full of the wrong people. I think agents and publishers are finally figuring out that a bunch of followers or likes or what have you mean absolutely zilch.
I'd go both if I were so inclined for awareness, however! from what I understand from some marketing gurus (and no, don't trust the gurus in all places) but for sales Twitter was apparently destroyed at some point for writers. Don't ask me how or why. So, if your goal is to sell, then I'd spend your time learning FB and its ads system, while building your awareness there.
Your right Demesnedenoir, that has certainly been my experience on Twitter and part of the reason I asked the question. To see if people had a better experience on Facebook.
It's not that a particularly want to sell sell sell, for me I just want people to know I've written the book in the first place.
I'm trying to plan my time next year around how much time to devote to the likes of forums, which I see this as communicating with like minded writers around techniques, story telling etc, and how much I need to spend just getting the word out. Personally. I'd rather spend more time here, you all have been great already! But I know ill need to do at least a little work on Social media.
The poll was to see where I should put my energy and time, over which platform was a more worthwhile experience.
I can really only speak to FB ads and boosted posts. Twitter, you have the advantage of just jumping #'s and maybe catching people's attention for free. I picked up my scant few followers there just by using the writing #'s, so I'm sure its workable. But! I get most of my readers through FB ads, and therefore interact most with those readers through FB. I probably should do more Twitter... but honestly, it's so flooded with politics I can't stand it. I followed agents and writers and lots of stuff, and it's just hard as hell to filter out the noise. I end up ignoring everybody. FB gives me the ability to focus without those distractions.
In a sense I see boosted posts a bit like Twitter... they aren't worth the same as engagements with ads, but followers still have some value.