I have two ideas for Houseruling the Beastmaster Ranger, mostly after reading 2 internet forum threads arguing about it.
The first is, instead of gaining any of your proficiency bonuses to its attack, AC, damage, or anything else, the beast just gets its own turn on the Initiative Order, with its own Action. So instead of making its attack and damage similar to a PC’s, it just gets to be an extra character for the Ranger to control. Very similar to how Summons spells work.
Second, and these are mutually exclusive, simulate the fear/craziness of having a BEAST attacking, by granting the beast advantage of every attack vs a humanoid, and making humanoids take disadvantage on attacks vs the beast. You are much less likely to fight a trained attack dog than a regular fella.