Of course widebody looks good on every CV, but forget about applying to jobs like x hours on 737 or y hours Airbus FBW. What you'll get is jet hours above 50/60 tonnes (it seems nobody cares about weights above these), and not particularly a lot of them.
It all comes down do T&Cs: if you like where you are, the money is good, roster is great and don't care about fast(-ish) upgrade, go for the old freighter. On the other hand, if you want a fast upgrade, chance to progress to a better/bigger company faster, fly new aircraft, long-haul, see the world or whatever floats your boat - stay on 737, build hours and look forward to a change of scenery.