Everyone loves the look of HC. Few people are willing to do Dry Start Method and high light/high tech to do it justice if they are just starting out.
I envy my club members who grow it, but it dies in my tanks
Still it's super popular.
Red plants esp intense red are always popular, but they need high light as well as the right ferts.
Just look on TPT to see what plants are selling fast, rare stuff or algae free/snail free nice examples of popular plants sell fast also.