The BEST shapewear cami I ever found was an underwire, full cup dream of a thing by Delta Burke, who doesn't make them any more, alas.  This one is the second-best.  Full coverage cups that don't squash the girls, underwire support that doesn't poke (yay!) and if you can resist the urge to buy one that's too small, it doesn't roll up or shimmy around.  Just be honest with yourself - if you need a 42, don't buy a 40.  Holds the jiggle in and smooths where it should, which means the fit is merciless and getting into and out of it requires some effort.

OK, Bali, honestly.  Some things could be improved.  The cup shaping is not perfect - not quite Madonna cone-boobs but those lumpy "petal" thingies could really go away.  Better under shirts & blouses, not so great under sweaters.  I'd buy it again, especially at the $20-ish price.