I have no experience with lee's filters, but looking at its design, go for the triple thing, it looks nice and the airstone is included. You will need an airpump for this.
I have a similar filter assembly, just a very old design, sits inside the tank (mine is Marina model 10891). The advantage is that you can mix different filter media. It's a back up filter in my 5.5gal male
betta tank.
For guppies, I think filter fiber or floss will be enough as media. You may need to add some weight (stones? plastic covered lead weights?) or find a way to attach it tho the bottom (using a suction cup to hold the airline might do it).
Whenever you rinse the filter media, remember to do so gently in tank's water or in treated tap water, even if it looks awfully dirty don't replace all of it, leave at least 1/3 of old media so you don't loose your beneficial bacteria.
Pepe
Santo Domingo