Class-Specific Feats 5E?

[sayaijin]

This post isn't necessarily to discuss balance between classes, but I'm working on feats that require at least 8 levels in a class. I want to reward my players that are single classing instead of multi. I've been focusing on martial classes.

Do you all have any I can use? How good are the ones I have below?

Combat Specialist
Prerequisite: 8 levels in Rogue
When you use your Uncanny Dodge, you can make a weapon attack against the creature attacking you.

Expert Hunter
Prerequisite: 8 levels in Ranger
You can now cast Hunter's Mark at will and it no longer requires concentration.

Frenzied Rager
Prerequisite: 8 levels in Barbarian
When you use your Reckless Attack, you can choose to roll an additional die with each attack, but your enemies can also roll an additional die with each attack.

Relentless Warrior
Prerequisite: 8 levels in Fighter
When you use your Second Wind ability, you also gain the same number of temporary hit points.

Martial Prowess
Prerequisite: 8 levels in Monk
You no longer need to spend Ki to dash or disengage.