Real plants help to create a more natural environment for fish. There's more work and money involved, but the benefits far outweigh the hassle/expense. My fish love 'em.
Real plants. Even if all you can grow is low light plants like me, they make the tank look great, contribute to better water quality, and the fish seem to be much more at ease.
I don't have fake fish so the plants are real too =)
Oh, sorry. I did have a "No Fishing" sign with a plastic fish when I was 12
Real ones do make the aquarium a better place for fish. If they are growing and doing fine, I mean. Dying and decaying plants won't do much good in a tank, but I don't think it's that hard to keep the easiest plants alive.
There are tanks where plastic plants are the only option if you want something green (besides algae) in it, but that's not the case in a normal tank with normal fish
You just need to know what plants need to thrive and what species would be good for your tank.
Tropica is a good site to begin your journey to beautiful planted tank