Maybe I should've been clearer, but was just trying to stick to same terms the OP was using. All things equal:

1) Sudden adoption: Both become centralized: Monero ❌, Bitcoin❌

2) Gradual adoption: Both remain decentralized: Monero ✅, Bitcoin ✅

3) Transaction fees: Monero becomes increasingly cheaper with adoption ✅, Bitcoin becomes increasingly expensive with adoption ❌

Also:

"Normal" txs: Monero is heavier❌, Bitcoin is lighter ✅

Private txs: Monero is lighter ✅, Bitcoin is heavier ❌