The faster the plant grows (which will be noted on most sites that sell them), the more toxic stuff
it eats up while growing.
Not to say that slower growers aren't useful...they help as well, just less so.
However, a dying plant can create as much waste as poo or left over food, so make
sure you check the light/fertilizer requirements for them.
Floating plants such as Anarcharis grows like a weed, so does Hornwort, and they are both pretty cheap.
Slower growers that are hardy are java plant, wendtiis, amazon swords, red flame swords...
I use fertilizer now to boost growth (Flourish by Seachem), but they were healthy without it.
I have the farthest thing from a green thumb for terrestrial plants but my aquatic plants are thriving