What's the options for the best transcoding settings?

I tried to transcode a movie to 2.5 times the bitrate for a 60 fps movie, but the image quality was really bad in terms of blockyness. What's the settings to enable handbrake's "medium" encoding preset for SVP's transcoding setting? Cause svp's "slow" is't  "good quality enough" for small sized movies i transcode with handbrake for my phone. Is there any slower better quality settings i can use?