Handbrake vs Adapter ?

I decide to using QuickTime Player X that is default on Sierra as only player on my Mac. For old videos and clips that wont's played on my Mac I can't select best encoding software. I try Wondershare Video Converter but seems it is not very good. Adapter is faster than Handbrake on my system (Core 2 Duo, 4GB RAM) and also based on FFmpeg, Handbrake seems has great settings with slow encoding(on my system).

Which is better as future-proof video encoding!?

There is any way to modify Handbrake to speed up encoding instead of default encoding profile!?

Thanks