If you want to become the best, separated from other killers, you need to get a killstreak kit and create a weapon with the same name. But if you want to stand out from other killstreakers, then you need to get the rarest variation of the kit - a professional killstreak kit.
Professional killstreak kit TF2 - is an item that allows players to get a unique type of weapon which includes a kill counter, colored sheen, and particle effect to the user's eyes. There are seven different types of effects, these will become visible after at least five kills.
Find a professional killstreak kit for the best prices here to be the best one on the server. On DMarket, you can also trade tf2 skins and get items that you really need.