In general, let's assume we are playing under 5.5 rules unless otherwise stated.

Exceptions can exist (making a 5E style paladin).

As DM I am not really concerned about power creep, I can always power up monsters.

My concern lies in what slows combat down. If player action economy goes up, it slows the game down. So, if I felt something needed to be banned/nerf, it would be in the spirit of speeding up the game.

This is a huge 'not set in stone' topic.