so here's a question. i'm ok at guitar. not great, just ok. i just need more time to practice.

but i would really like to improve how to write music, not how fast i can play. would piano lessons help me to improve in that way? or should i just take guitar lessons?

thanks in advance!
Playing more than one instruments is always a good thing.
Epiphone G-400 Ebony
Line-6 UberMetal, EchoPark
Boss RC-2 Loop Station
Traynor YCV50Blue, Bass Mate 25, Guitar Mate 15