Fluval filters are pretty decent I think.
I had a Fluval Internal U2, did exactly what was supposed to do. 2 compartments for sponge media as well as carbon but did not use carbon, just added extra sponge. 1 central compartment for ceramic media.
3 water flow options as well as a Venturi option on fastest flow.
Access was easy and pretty good TBH to take out of tank and maintenance cleanse if and when as necessary.
Impeller access easy as well.
A well thought out internal really.
A little bit bulky and takes up space inside the tank is the only reason why I changed to an external filter. I still have the U2 as backup just in case.
Does exactly what it says.