Pirates of the Burning Sea (PotBS) has 2 game versions:
Legacy require a Subscription providing access to the Legacy Servers and account benefits (the benefits apply to all servers on both game versions).
Legacy is an old build requested by the part of the community not liking the changes made to the game, mainly in the 2.14.x - 2.15.x era.
You can choose to play on either server, but remember: PotBS is an international game, with a lot of players from different countries around the world playing across all of its servers.
The difference between the two servers are the Port Battle (PB) Windows. Antigua is an International server focused on prime-time USA Players, while Roberts as an 'European' server is focused on prime-time EU players.
That being said, it makes little sense to play on Antiqua for Port Battles (PB) as a player from Europe with a daily job. Most PBs will take place in the night. Likewise, it makes even less sense to play on Roberts as a player from America, the PBs will then take place in the (early) morning.
All servers had the new Port Battle Scheduler applied in 2023.
All servers are geographically located in the same location, so ping is the same for all servers.