You may command the beast to attack as a bonus action, rather than only as a command during the rangers attack action.
Ready Companion. As a bonus action, you can command the beast to make
its maul attack or to Hide.
They are also more robust, the Ranger may revive a beast of the air/earth at the end of combat if they perish, whereas with other beasts the Ranger will have to spend 8 hours magically bonding to a new animal.
It appears dissatisfaction in the class was related to the survivability of the beast companion, it's hampered attack options, the number of available spells per day and specific class features; favoured enemy, primeval awareness and natural explorer.