Four Juniper / Sycamore and four N is pretty standard for most decks. I've heard a lot of varying opinions on Shauna. Some people say it's good, and some say it's mediocre. I thinka vanilla five cards after a shuffle is on the weak end of the currently legal Supporters, but interestingly, Shauna is never a bad play. There's times when you do not want to give your opponent a hand refresh, or when Colress would give dismal results, such as the early game. In the mid-late game, Colress averages 6-9 cards, which is above Shauna. Still, I often run one of them.
I've also seen a few players run a single copy of Bianca. This was seen in Worlds top four finisher Michikazu Tsuda's Crazy Punch deck. I could never make Bianca work personally, but having it as the last card in your hand and drawing the full six is almost as nice a feeling as doing that with Sycamore. The only problem here is that Bianca serves no use if your hand is full of seven or more cards that you can't play. A jJnuper / Sycamore in this case would let you trash your hand for seven new cards. Still, Biance does have a bit of utility. It's Cheren/Tierno that I think is the least effective draw Supporter. Compared to what the others can do, drawing three cards is... meh for a Supporter. Don't even mention Battle Reporter in front of me.
I'd also like to take a minute to mention Item-based draw. Bicycle is probably the most powerful, as there's no drawback to it. I include at least one in almost every deck I build, since it nets you more than what your Supporter for the turn got, or you can use Skyla / Korrina to pull it out of your deck. Roller Skates is another fun option. The potential for three cards off an Item can put you ahead of the game... if you flip heads that is. However, running four of them will maximize your odds of success, and they really can make a difference if you can squeeze them into your list.