In the past couple of years, I would say LT hands down. This year it's a little more difficult. Brady had such an insane year last year...
RB's are by far the most in-demand position in fantasy football. The league turnover at the RB position is very high and more and more teams are going to a RB by committee.
However, since your league starts 2 QB's (most leagues only start 1), QB's will be in high demand. And good QB's tend to drop off after 12 or so. RB's drop off as well but everyone in the league will be essentially dealing with mid-tier RB's. Basically what I'm saying is that you'll have more mid-tier RB's to choose from than you will QB's. After the 1st or 2nd tier of QB's, fantasy production drops VERY fast.
Grab Brady then take the best WR and RB available with your next two picks, which, since it's a snake draft, will be back-to-back. Always a good thing.
So here's what I would do:
1. (#1 overall): Brady
2. (#20 overall): best RB available
3. (#21 overall): best WR available
With your next two picks, I'd do the same again, or maybe swapping one for another good tier-2 QB if one is available.
Essentially, my strategy would be to get at least one good QB, RB, and WR, and even a 2nd in each category, before worrying about the rest. You could maybe take a TE if you can get a tier-1, otherwise, I wouldn't worry about it. Best strategy is to take best player available once you get at least one in each category.
