I am going to have to say I do not have a favorite on this question. I would have to reach out to my players and ask them what their favs are. We do not do a ton of House Rules in my group. We tweak things here and there so yes we do House Rule. But there is very little that we make rulings on that stand out. Most are just small tweaks to make the game flow better and shortly after become forgotten and just the way of things. So I will go with a great example for my group.

When 5E launched I shifted my campaign over to 5E. One of my players wanted to play a Shifter. As the race was part of my homebrew world. But there was no 5E version of the Shifter as of yet. So we sat down and cobbled the race together. A few months later. they put out the race. We compared it saw that they were very much in line with one and other and kept our version of the race.

Our Longtooth

Longtooth Shifter

• Ability Score Increase:  Your Strength score increases by 1.

• Savage Assault:  When you roll damage for a weapon attack, you can roll an extra weapon damage die and add it to the total. This added damage doubles on a crit. You must determine whether or not to use this ability before you roll, and a miss the attack is wasted. You can’t use this feature again until you finish a long rest.

• Biting Finish:  If you hit with a melee attack, you can use a bonus action to make a special bite attack. This attack does 1d4 damage plus your Strength bonus.

WOTC. 

Longtooth As a longtooth shifter, you are a ferocious combatant. Ability Score

Increase. Your Strength score increases by 1.

Shifting Feature. While shifting, you can make a bite attack as an action. This is a melee weapon attack that uses Strength for its attack roll and damage bonus and deals 1d6 piercing damage. If this attack hits a target that is your size or smaller, the target is also grappled.

Our Razorclaw

Razorclaw Shifter

• Ability Score Increase:  Your Dexterity score increases by 1.

• Fleet of Foot:  Your base walking speed increases to 35 feet.

• Shoving Charge:  If you move at least 20 feet straight towards a creature right before hitting it with a melee attack, you can use a bonus action to attempt to knock the creature prone as if using the “shoving a creature” special melee attack. See page 195 of the 5th Edition Player’s Handbook.

Razorclaw As a razorclaw shifter, you make swift, slashing strikes in battle.

Ability Score Increase. Your Dexterity score increases by 1.

Shifting Feature. While shifting, you can make an unarmed strike as a bonus action. You can use your Dexterity for its attack roll and damage bonus, and this attack deals slashing damage.