Canister filters are most desirable and also more expensive.
For 90litres i woud personally recommend an eheim 2213 or fluval 206.
I have a 2213 but not the 206, i do have a 406, both are good filters and you cant go wrong with either but if i was pushed into a chosing i would buy another eheim.
I guess it depends on what you want and what sort of bioload your going to have in the tank.
Internals: they take up more room inside the tank, can be an eye sore, Theyre cheaper, you will pay half the price for a fluval U4 rated at 1500lph than an eheim 2213 canister rated at 440lph.
Canisters: more media for bacteria growth, less equipment visible inside the tank, easy to clean and detatch from the tank and obviously they're more expensive.
Again depending on what you want to use it for will probably donate which is more appropriate. Display tanks then a canister. Large lightly stocked tanks where pump has more of an importance over media for bb growth, then internals. Both will do the job of filtering your water so choose whats best suited for you.
Fish die belly upward and rise to the surface. It's their way of falling.