For a party? Paintball. If you plan on ever doing long term like starting a team or becoming a regular player, airsoft.
Paintball is fun because it's generally more fast paced and scarier and more adrenaline rushing due to the fact that the paintballs hurt more. However it's a hard hobby to maintain because the equivalent of a $300 airsoft gun is around $1500 in paintball. Airsoft also has milsim, which is especially fun.
But you're asking for a party so do paintballing.