It may vary depending on how often your PCs are up against other PC-race foes, with class levels, and how often they're up against foes from the Monster Manual.
I imagine that spells which work against INT saves, such as Phantasmal Force, are very effective against most beasts, much more so than spells vs STR DEX or CON.
Eldritch knights get proficiency with CON saves, useful for concentration; paladins and rangers do not.
Hm. Sorcerer is a caster class with CON saves. Might be an argument for starting as Sorcerer, then go Warlock or Bard (which also use CHA as casting stat). Paladin is also CHA-based, but Sorcerer-Paladin seems thematically rather oddball to me.
Then again... wild magic, Oath of Ancients. Wildly passionate devotion to light and hope. A CG Paladin? I'd kinda like to try it as a role-playing exercise.