Not long ago I posted a poll up in the sidebar and asked everyone what their preferred filter of choice was, and the results are now in so, be sure to come by again to participate in the next poll!
The top two choices for aquarium filtration were Canister filters at 46% and Power filters at 26%. Sponge, Undergravel and some Other type of filtration were all tied at 20% which left Wet/Dry filters at 6%, and no one appeared to like Internal filters which showed at 0%.
As for my opinion on the best filter, it really just depends on your setup and what you want to achieve.
Canister filters are great if you need something that can house a lot of beneficial bacteria, but I don't find they always clean the best, although you can add inline UV sterilizers or inline heaters so they are pretty customizable in terms of what you can do.
A Power filter I find can generally clean better than a Canister filter, but they often lack the capacity to hold a lot of beneficial bacteria which a Canister is more capable of doing. Generally, a Power filter is not as customizable as a Canister filter but Power filters are becoming move advanced with bigger boxes to house more media and built-in UV sterilizers (which before this was mostly a Canister filter feature).
Both Sponge and Undergravel filters have their place in the aquarium world, but they often don't offer any media benefits, they aren't that customizable and personally, I find them to be more of secondary type of filtration used alongside a Canister or Power filter. They're good if you don't want a lot of water current in a tank, or if you need more surface agitation, and personally the Sponge can give a little beneficial bacteria while an Undergravel filter is really just made to disperse gas from waste and cycle water with carbon which helps to remove discoloring and water chemicals.
Wet/Dry or Sump filters are very similar to a Canister filter but they're generally on a much larger scale. The reason these may lack popularity based on this poll is because they can become costly and it takes some amount of knowledge at times to set these up properly. These do allow for more water aeration in comparison to the other filters mentioned on here. For large aquarium setups having one of these can practically double a tank's water capacity.
Internal filters are pretty similar to Power filters accept they take up much-needed aquarium space inside the tank and they aren't always that attractive to look at. Most the time I see people recommending these for shallow water pets such as frogs that can go in the water or on land.
As for other types of filters, there are new ones I hear about all the time and recently one of those is a Trickle/Shower filter. This type of filter is similar to a Wet/Dry filter although it usually sits above the water rather than below it. You'll also find Moving Bed and Powerhead filters, and I'm sure some other types that I can't think of at the moment but this should cover the most popular of filters you'll come across in the aquarium hobby today.
Also, big THANKS to everyone who helped participate in my poll because you helped to make this post possible.