I think the respect option of Pathfinder, both Kingmaker and WotR, is the optimal one. You can respect everything that comes *after* your first meeting with a character. Everything that came before, is part of the character itself and of its identity, both combat-wise and RP-wise.
The thing about Pathfinder, however, is that there are many options as you level up and adventure that make it easier to customize a character. You get a +1 to a stat every 4 levels, a feat every odd level PLUS bonus feats from classes, and - perhaps the most important - a plethora of ~guaranteed magic items that give bonuses to stats. Characters can wear ~10 magic items at a time with the head and belt slots being practically reserved for these stat-increasing items, and you're expected to find/buy them in your adventure.
Whereas in 5e, customizing stats and abilities is much more limited. You get a +2 to a stat OR a feat every 4 CLASS (not character) levels, and items that increase stats are fairly rare and take up a valuable attunement slot. Additionally, the more common D&D stat-increasing items Set a score to X, meaning we've either wasted any points invested in that stat or have to suffer with that stat being low until (if) we find that Belt of Giant Strength.
This isn't necessarily an argument for allowing respeccing of BG3 Companions, just that customizing a character through leveling up & magic items is more limited in 5e than in Pathfinder.
p.s. Oh also I almost forgot to mention skills - Pathfinder has skill points as you level up, whereas 5e doesn't. You don't even gain new skill proficiencies when multiclassing.
