Sometimes picking up some mechanics your first class doesn't give you is key to making a character's mechanics match their personality.

Like I had an Echo Knight Fighter whose wife was killed in an ambush by a vampire, and he became a vampire hunter with his wife's ghost as his echo.

Then, I wanted to multiclass into Ancestral Guardian Barbarian to try out that combo. So I made the Ancestral Protectors his mercenary friends who also died in the ambush, and it worked really well.

But he still wasn't especially good against undead, he was just all around a badass, so I grabbed some Ranger levels to get Favored Enemy and made him a Hunter for a bit of horde clearing, since the vampire he was originally hunting had joined a cult that raised hordes of undead.

All of these were mechanical choices, and very strong ones at that, but they also made the character fit his backstory better than just being a level 20 Fighter would have.