They both are special in their own way and both of them signify the reward for having patience. Both of them require patience to evolve - Magikarp is hectic to level up because it cannot fend for itself, while Feebas has to maximize its beauty.
They do have similarly low stats, but Feebas is much more rare, while Magikarp is common. (Inverted in Unova, if you do not count the salesman who gives you the Magikarp, as you have to complete your Unova Pokedex to catch one otherwise in B2W2, while it is impossible in BW.) Feebas can learn TMs, which is an advantage over Magikarp, which kind of makes up for its ugly appearance. Upon evolution, though, Gyarados has a better movepool than Milotic when it comes to variety, but cannot use all of them well.