Hi {{first_name}},
I've reviewed the full offer for [[job title]] and I'm ready to move forward. The role, the team, and the direction all feel like the right fit.
The one thing I'd like to adjust is [[specific component: e.g., "an additional week of PTO" or "a $5K professional development budget" or "a start date of [[date]] instead of [[date]]"]]. If that works on your end, I'm ready to sign.
[[Your name]]