Man, near impossible question to answer at it is so situation dependent.
10 team or 12 team league (or bigger)?
PPR or non-PPR?
Lineup requirements?
Superflex or not?
If a longstanding league, draft tendencies of the league overall (ie are the RB hoarders, QB early, etc.)?
Then once all that is taken into consideration, a lot comes down to just who falls to me. For example, in most setups, if I'm sitting at 9 or 10 and Michael Thomas is still there, I'm probably taking him as that likely means more RBs were taken in the top 8-9, so my RB option is weaker, and it also means that there is less value gained in taking the RB in the 1st over waiting for the turn to take one, if I were inclined to take an RB in the top 2.
If I know it is a league full of RB hoarders, so much so that they will take that 3rd and even 4th tier RB in the late 2nd/early 3rd over top WRs, then I am more inclined to go RB/RB at the turn, as I know in general I am still looking at stronger than usual WR options at the 3/4 turn.