Summary
The actual answer for "best" at 735:
3. Feral Druid (Yes, really)
Why it wins: Chaos Strike damage scales quadratically with Crit (doubles crit chance via First Blood talent). At 735, with 45%+ crit, Havoc becomes a slot machine that pays out jackpots. The legendary Anger of the Half-Giants (fury generation) enables near-permanent Metamorphosis uptime in M+.
The strength of these classes at the end of Legion was driven by: Tier 21 Set Bonuses
You cannot be “better” with default UI. Use:
: Many classes reached their peak power in 7.3.5 due to the final raid tier's equipment bonuses, which drastically altered rotations and power levels. Legendary Synergy