Ill go over each of the final evolutions.
Beedrill
For a Pokemon that evolves at level 10, it has a pretty high Attack stat (90) and is pretty fast (75), so it can be extremely useful early on in-game. (it also gets a unique dual type, Bug/Poison)
Butterfree
Butterfree unlike Beedrill, has a dual type of Flying/Bug.
The good things about Butterfree are it's high SpA stat (90) and it's moveset of status moves (Poison Powder, Stun Spore, Sleep Powder) and like Beedrill, it can be extremely helpful early on in-game as it evolves at level 10.
Vivillon
Vivillon is basically an upgraded Butterfree, as it has the same SpA stat (90) but a higher Spe stat (80) plus, it has a pretty high HP stat (80) plus it learns all the useful Status moves Butterfree learns (Poison Powder, Stun Spore, Sleep Powder).
it also has the same dual type of Flying/Bug.
The only "problem" with it, is that it evolve 2 level after Beedrill and Butterfree, at level 12.
All three are basically the same, early-game bug types that evolve at extremely low levels. and can be extremely useful early on in-game.
Out of the 3, Vivillon is the best as it has the best Stats and learns some pretty good moves.