Joining a covenant gives you two abilities: covenant signature abilities and class specific abilities. Blizzard's goal is to create depth via choice and consequence. The protest from players is that the strongest abilities will be a much larger influence in choosing a covenant than aesthetics or lore.
Proposal: players choose a covenant and receive a signature covenant ability (unchanged from current beta). However, class specific abilities are unlocked, and available to you regardless of covenant choice. This satisfies Blizzard's requirement for user choice and consequence while greatly lessening player pressure to pick "the best" covenant (and the headache of having to balance the class abilities).
This idea could be modified as/if needed (for balance) so that the initial class ability is immediately available after pledging allegiance while the others must be unlocked.