Waifu Option : Dorothea

Main Character
Byleth - close to unbeatable late game if pumped properly - level to mounted / flying to utilize her enormous strength in battle late game

House Characters

Edelgard - Fortress Knight - powerful tank - almost unbeatable
no longer playable late game - story related

Hubert - Warlock - super strong DPS
no longer playable late game - story related
Ferdinand - Paladin to Dark Knight / Holy Knight
This character is truly strong as a knight, leveling him as dark knight makes him super strong / also if you level him as Holy Knight makes him a super mobile healer and killer

Bernadetta - Run of the Mill archer character with her cute hikikomori antics - level her to Bow Knight to become strong and usable

Linhardt - Generic healer archetype - Bishop / level a lil bit of Reason for dark magic accessibility

Petra - Falcon Knight - Level her flying and lance skill early to access the Flying class ASAP to unleash her character's prowess

Dorothea - Gremory class - White & Dark Magic combo character - can kill can heal - Pure DPS / Off-hand heals

WORST CHARACTER
Caspar - Run of the Mill melee character - you need to change his class to a flying / mounted class to offset his character disadvantages

Character Powerhouses
Catherine - Caspar's replacement - Side Character with God-weapon
You get her mid-game, she can replace Caspar and has better stats than him, with a legendary weapon in-hand, she clears the field easily but needs more mobility so Flying class are great for her

Shamir - God-tier archer - Crit Goddess - fully master all bow-type classes to bring this Ranged Goddess
You get her mid-game but she is already powerful even with just an iron bow

Seteth - Flying Killer Lance - Demon in the Sky - Wyvern Lord class
Mid-game character as well - unbelievably strong and the most mobile character in-game

Flayn - God-tier Healer - Muh AOE heals - Gremory Goddess / Holy Knight as super mobile healer / Falcon knight as flying heals
Mid-game character as well - didn't understand her at first then found out she is super OP. Lacks single target heals
Side character and Other character
Manuela - never used her - no comment - disappears from game
Hanneman - never used him - no comment - disappears from game
Cyril - weak character late game - almost pointless to level due to so late in getting him
Other houses character just brief appearances
Dedue - a true walking fortress - nuff said
2nd playthrough start: Golden Deer house