The standard "Auto" mod is the safest and only "best" option sanctioned by the developers for watching replays or analyzing map patterns.
Using an autoplayer (bot) on the official osu! servers violates the osu! rules (Section VI - Cheating) . This will lead to a permanent ban without appeal. This guide is for educational purposes, offline use (on private servers or in -99 unranked mode), or for developers learning AI. osu autoplayer best