The best practice currently is to give people P2SH SegWit addresses when people are paying you, but to support/allow sending to bech32 addresses when you're paying people. bech32 addresses are strictly superior except for issues of backward-compatibility, so eventually everyone will switch over, but it'll probably take a few years; it shouldn't be a format war situation unless someone decides that they hate bech32 and come up with a totally new alternative.