I need the most absorbant diaper out there...

I have this really bad wetting and messing problem and nothing seems to work. Everything I use ends up leaking... so I need the most absorbant diaper out there. (maximum absorbancy)

Rearz Safari or Inspire+InControl and ABUniverse PeekABU are probably the highest capacity (liquid) going. But they're not cheap, and you have another thread going about how to pay for your diapers, so I think you better work on that first.

I have the same problem as I drink diet Coke. The only solution to get me through 7 hrs of sleep at night is a combination of BetterDry diapers (Large - 39" waist) and two or three six ply Gerber cloth baby diapers folded inward to make a thick booster. To ensure no leakage, I wear a double terry cloth panty over which I wear a Large Leakmaster PUL diaper cover. I rarely get leaks - but sometimes the terry cloth panty gets damp on leg openings. I usually have four or five panties to alternate and provide wash/dry times.
I have found that BetterDry diapers from NorthShore Care Supply in Chicago offer 5% discount on regular subscription orders (i.e., order 60 diapers every seven weeks). Usually delivered within two days no shipping charge as I live in adjoining state.
Their Supreme and Air Supreme diapers are good too, but by themselves don't last more than 4/5 hrs for my elimination routine.
They have a chat line if you wish to inquire.
Leakmaster PUL diaper covers are good as they don't get hot and breathe. Make sure you measure your leg size at upper thigh to get proper fit.
Hope this helps.

I agree. Betterdry is by far the most absorbent and capable diaper out there. Combined with pul pants you will be well protected.