Water pillow or Boveda humidity pack

[T.G]

I'd go with the Boveda.

Pro
Thinner = more space for cigars
Less likely to leak or weep = less chance of ruined cigars
Bi-directional humidty control = besides raising RH, it will bring RH down if it's too high, somehting that water pillows don't do.

Con
Harder to recharge - have to seal it in a tupperware with a shot glass of distilled water for a few days, versus simply dipping a water pillow into water for a few seconds.