Probably one of the closest in stats in the category of infamily evoluton, Scyther and Scizor compete very close against each other.
Scyther is one of the original pokemon introduced when pokemon was released. Although it has a huge rock weakness, it is quite faster than a Scizor would perhaps be. The movepool is a little light, but it is a great offensive pokemon.
Scythers weaknesses include Ice, Rock, Fire, Flying and Electric. 5 major weaknesses. The movepool is very light, they are not the best on the defensive side, and overall, are slightly above average.
Scizor are the favored pokemon in the Standard OU metagame. Bullet Punching and Swords Dancing can be a bit tough to deal with. This pokemon has a wide movepool that contains X-Scissor, Iron Head, Fury Cutter, Bullet Punch and X amount more. Scizor's were considered a bit scary and rebellious over the years that it has existed. It has always has a brother (Scyther) to compete with.
Speed. Scizor's are not typically fast, considering it is a mantis covered in thick iron (I believe?). If you come across a fire type with this pokemon, your toast.
So, which one shall it be? The slow but heaving hitting Scizor, or the Fast but defensively prone Scyther? Your vote. Discuss -_-