I would not go with the Aquia because of the small water area in the bowl, this goes for all of the dual flush toilets on the market.
I would look at something that has a high gloss finish in the Toto line they call it "Sanagloss" it won't stop it getting dirty but reduce and will make it easier to clean or clear.
I would also look at something that has a good rim wash, in Toto it is the "Double Cyclone" flush and it also does not have those holes under the rim that get dirty.
The Drake II (Gwyneth) would be my choice for what your looking for it is #CST454CEFG it also it "Universal Height" better for getting up and down and also it only 1.28gpf.
You would have to check your local store for the price but Terry sells them for $354.99.