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 ❌