I may be teaching granny to suck eggs but make sure you buy multispeed chain, assuming you're using a regular rear derailleur. Single speed chain (1/8" width) is too fat to use on a multispeed (3/32" width) rear end. Also there are differing multispeed chains which all essentially appear the same but those destined for 9, 10, 11 speed etc applications are thinner in the chain plates as these rear cassettes pack the rings closer so make sure you buy something compatible with the number of speeds. If you intend to add a potent mid drive (front mounted on a Warrior) motor at any point the chain is also going to have to transfer that power so don't buy the cheapest. A reasonably fit rider may put out 250W or so, a top athlete 400W, a Bafang mid drive motor 1200W or more at peak.