Which is faster?

I'd say glosso
but then again - if you get dwarf hair grass you'll have a lot of stems and if you plant the stems spaced out it can get thick pretty quick

i have both, glosso is slightly faster, i've seen local people plant glosso and hair grass by the node, but i'm too lazy for that,
i usually plant them in chunks and then let it spread and grow in on its own and then trim if necessary to keep it in check