Tricky one that. . .
Personally, I think I'd take the command on the ATR, but the next person might say completely the opposite.
I know people that have taken commands on ATR's over a RHS in an Embraer - it's a good type for a first command and will look good on paper too.
I'm in this job for the left hand seat, so from my point of view, I'd take the command. . . .