Hitmons is a fan term used to refer to the three evolutions of Tyrogue (Hitmonlee, Hitmonchan and Hitmontop). The name comes from the prefix shared by all three Pokémon, hitmon. The Hitmons all have low HP, high Attack, high Special Defense, average Defense, average Speed, and low Special Attack. All the Hitmons are male and are pure Fighting type. The Japanese equivalent of the hitmon. In the Nintendo Player's Guide for Pokémon Stadium 2, they were referred to as the Tyrogue squadron.
Hitmonchan :
Hitmonchan evolves from Tyrogue when Tyrogue's Attack is lower than his Defense. Hitmonchan's most notable ability is his wide versatility in boxing--his major attacks are almost all punches, such as Bullet Punch, Sky Uppercut and the three elemental punches. In Generation IV, he also had an Ability exclusive to himself: Iron Fist, which increases the base power of punching moves.
Hitmonchan is a tan colored, human-shaped Pokémon. His body resembles a light purple tunic with a skirt and fists that resemble red boxing gloves. His enlarged shoulders give the appearance of shoulder pads, while his purple feet give the appearance of a pair of boxer shoes. Unlike his parallel evolution, Hitmonlee, he has a mouth and a visible separation between body and head. His English name contains a reference of Jackie Chan, while his Japanese name is derived from Japanese world champion boxer, Hiroyuki Ebihara.
In Red, Blue, and Yellow, as well as FireRed and LeafGreen, Hitmonchan can be chosen as one of the prizes for beating the Fighting Dojo in Saffron City. In other generations, he is obtained by evolving Tyrogue.
Hitmonlee :
Hitmonlee evolves from Tyrogue when Tyrogue's Attack is higher than his Defense. Hitmonlee knows several kick-based moves, including his former signature moves Mega Kick, Jump Kick, and High Jump Kick, and the rarely seen Blaze Kick. His leg muscles have the special ability to freely stretch and compress. In Generation IV, he had an Ability exclusive to himself: Reckless, which increases the base power of moves that can deal recoil damage.
Hitmonlee is a brown colored, human-shaped Pokémon. He has three-fingered hands and three claw-like toes, and has segmented, cream-colored arms and legs. Hitmonlee has almond-shaped eyes with black rings around them and appears to lack a nose, mouth, and neck. His English name contains a reference of Bruce Lee, while his Japanese name is derived from the world's first kickboxer, Tadashi Sawamura.
In Red, Blue, and Yellow, as well as FireRed and LeafGreen, Hitmonlee can be chosen as one of the prizes for beating the Fighting Dojo in Saffron City. In later generations, he is obtained by evolving Tyrogue.
I will say if you choose Hitmonlee it will be great and better then Hitmonchan cause Hitmonchan is Lower in attack then Hitmonlee and some stuffs has some little Reference
So you can see the different in attack and speed but if you think Hitmonchan is better so go choose it and don't think Hitmonchan is bad moth are powerful ;p