buy the heavier one

  The basin wrench:

Fiddly to use, but no one (not even Ridgid), has come up with a better design.

 The first one I bought - with a different house, in a different wife - was some random inexpensive store brand.  It broke after maybe a dozen uses; the handle tore out of its holes.  I was also young and dumber; I may have used a bit of cheater pipe instead of heat to get antique fittings apart.  Ahem.

 So I asked around my circles, "what do pipe fitters and plumbers* use?"  Mostly, I got one word: Ridgid.
So I bought the Ridgid.  I believe Ridgid expects users to abuse the tool because the handle torque is applied to the hollow shaft not through its holes, which are a bit too large, but via a solid piece of square stock nestled inside the shaft, to wit:

 I've been wrestling with another very old (probably installed in the 1950s) enameled cast iron sink in my shop bathroom, replacing a supply line.  I put, oh, however much my weak-ass biceps are good for yesterday... let's say 45 lbs... onto a foot-long adjustable wrench onto the hollow shaft, and while the fitting did not come off (I'll use the torch today), that wrench was nice and stiff.  And did not slip off the fitting either. 

 Not a commercial, just a reminder that you get what you pay for:

made in USA - I checked