I'm a bit wary of most of the internal filters, they seem like they take up quite a bit of room, and are more difficult to change/maintain.
I haven't really done a riparium setup, but I've done a few paludariums, and usually just built a filter into a waterfall.
You might want to consider something like a hamburg mattenfilter- if you get the proportions right they are supposed to require nearly no maintenance. And you can stick the heater behind it.
Then again, if you have a riparium with emergent plant growth, you may not actually need any filtration depending on your stocking levels - the plants may be able to handle all of the waste.