Q. Who do I send my demo to?? I don't know who to pick??

It's a crucial decision and you're wise to give it a lot of thought. Don't send it to a label who may already have an artist similar in style to you. That said; don't send to it to a specialist label if you do not fit into their genre.
If there's a company with many of your favourite artists on the roster that you think you would fit well with, give them a try but take the time to find out a contact name and they may return that time and effort by listening to it.
Don't just send it because you happen to have recorded an album's worth of songs. Only send it if you genuinely think it's ready and brilliant. If you're not totally happy with it, why would they be? This is a huge step so don't waste it. Bear in mind you may not hear back from anyone so after a couple of weeks, give them a call to see if they have received it and if/when you can expect it to be listened to.