Depends on what you choose/think
Melee Weapons:
1) Supposedly the dachi is the best but that does not mean it is. its just a katana with 3 augments. i could make a weapon thats better for example. i bought a master hammer (the hammer does 101/107 damage by itself) with 2 augment slots, i put a luck charm which makes it much stronger and the goul augment which drain apponets enegry and gives it to me it is way stronger the the datchi also i tested this out, i did one hit with each, the hammer killed the gaurd in 2 hits while the datchi killed him in 3 so ya but that is one reason
Range Weapons:
1) The red dragon is probably one of the best guns in the game, it can shoot 6 bullets really fast and reloads in 0.75 secs it does 47 damage per bullet with all damage put together it makes (282 Damage) , but then again i put the same augments (lucky charm & devestation) on the master turret pistol which does 67 damage per bullet but its reload time is 1 sec per bullet all together it does (402 damage).
2) It depends on what you like to, i perfer this over my red dragon it might take longer to load, but the enemy will never touch me because there heads will be shot off.
3) it says the perferator is better then the red dragon but i don't know, i never use it so meh.
All together, weapons are weapons but if you put certain things on them they become better and stronger.
hope this helps you.