I'd prefer Hillenbrand of the two, but neither one are hitting that well recently.
Here's how they stack up for the last month:
Games: Hinske 24, Hillenbrand 23
Runs: Hillenbrand 12, Hinske 11
RBI: Hinske 9, Hillenbrand 8
HR: Hillenbrand 3, Hinske 2
SB: both have 1
AVG: Hillenbrand .260, Hinske .224
OPS: Hillenbrand .693, Hinske .660
Not alot of difference OR help from either.
The lineup around Hinske is weaker and might get worse before the deadline. The Sox are in the market for another good bat, that favors Hillenbrand. Hinske will probably do nothing the rest of the way, Hillendbrand will probably be servicable (I'm guessing .275 AVG, 8-10 HRs, 35-40 RBI would be GOOD NUMBERS to expect from here on out).
I wouldn't dop either if it's a deep keeper league though. But agree with Jorge, in that you might ant to trade Hinske while his early season stats are still inflating his numbers.