I voted 45s but 27-90 or 180s are fine by me too. I like mtts alot so i treat these type of s&g as mini mtts. Like jimbojim said too, you get a better payout when you do well.
9 player for me, same reasons stated before, easier to read the table and make the money. Never understood 18; 9 more players, only one more spot pays. Need to get back to bigger MTT's, though, just for the bigger jump.
There's no option for (0), or don't like SNG's. I voted for 9 because every once in a while I will get a fix for a sit n go and that's usually what I play. For me it's been either a 9 seater or 180 seater in the rare even that I play in them.
The way I look at it, you could get 1st place once every 14 45 person SNGs you played, and not cash at all in the other 13, and you would still break even. That's why I usually play those.
I prefer shorthanded SNGs mostly because I feel like that is where more skill is involved than the 9 or 10 handed SNGs. When I play 9-10 handed SNGs, I feel like I have to play tighter and wait for cards. Shorthanded I have no problem playing LAG or what ever I feel will be best to win that specific tournament.