This is sort of off topic, but I was recently looking into Fighters and it seems like at higher levels, certain builds become very powerful in comparison with Berserker -- at least in terms of damage output.
For example, Battle Master with a Maul/GWM/GWF can use Trip Attack then use GWM swings for their following attacks. They can combine this with Action Surge and also Riposte, Disarm, etc. Disarm is amazing -- caster has a staff? Make them do a str save then pick it up or kick it away with your free object interaction. Or, make that knight drop their shield so your GWM feat is better against them.
They have a dramatically better "Fear" ability than Berserker in Menacing Strike, can reroll saving throws in a similar fashion to Fanatical Focus, and can even take advantage of some Charisma investment with Rally or the Inspiring Leader feat since Fighters get so many ASI/Feat slots.
So, of course Barbarian gets damage resistance and is more tanky perhaps, but Fighters get to wear plate and don't give their opponents advantage on them (and can forgo Dex investment if they want to put those points into something else -- Barbarians are more or less locked into probably 14 dex for medium armor).
I enjoy playing Barbarians more from a roleplay/flavor standpoint, but in the late game it seems like they get passed up in damage output by some of the Fighter subclasses and are also just more "boring" to play turn by turn since Barbs usually just do the same rotation. Even Berserker while using Frenzy and Retaliate only really beats Battle Master in very niche scenarios. You basically need a very prolonged sustained fight against an enemy that cannot be Trip Attacked in my estimation. Otherwise, Battle Master has some insane Burst with Action Surge/Trip Attack/GWM and solid sustained damage to boot. And just a lot of cool creative stuff to do like knocking enemies into pits of lava with Push Attack for example. Only gripe I have with Battle Master is that many of their maneuvers are objectively awful (like Sweeping attack/lunging attack -- these scale horribly).
I really wish Berserker was a bit better than it is

I've got a real soft spot for them. Maybe i'll just start playing Battle Masters...
Originally I felt it would be too powerful to simply turn Frenzy into an "Extra Attack" that doesn't use the Bonus Action, but after looking at other things that exist via stock 5e, I'm not so sure that that would be OP since it would still come along with a level of exhaustion.