Standing abs, cable crunch... same shit. Internet is filled with "awesome breaktrhough" advices about exercise variations, magical set/rep combos, diets etc. Now wonder people get all confused about what to do.
Even in this very site you see articles that goes something like: Tip! Do this (random weird exercise) to maximise your (random muscle) development! Or: Tip! Do these (random set/rep scheme, exicuted in a strange stance/machine/slow/fast/eyes closed..) to maximise your (random muscle) groth rapidly!
These seem to be written by same guys all over again, every week/month/year.
Then there are few, who preach about basic movements, hard/consistend work, proper nutrition, importance of sleep etc. These guys usually have couple decades of training/coaching under their belt and some numbers to show. They stand behind their principals, even though they know its not sexy and many wont listen, cause no one wants to hear that there is no shortcuts to get stronger/better.
I know whos advise I would trust.
In short; Tip! Do Ab wheel/Hanging leg raises/Sit Ups/Back Raises/Reverse Hypers for strong middle section.