Spent last night bouncing around the shards.
Bloodiron (PvP shard) is deserted (currently) , I ran two unstable events and saw four other players, three defiant and one guardian, so there was very little competition for the artifacts. I hung around afterwards until my artifact potion ran out and collected dozens, they were littering the ground, as well as loads of harvest materials. Even if you aren’t PvP geared I’d recommend Bloodiron for unstables and harvesting, the low population means that while you may get stomped one or two times it’s still far less hassle than competing with loads of other players.
Typhiria has about the same population as Gelhidra, and Zaviel has higher, so they’re great zones for standard events as the large number of players combined with shard hoppers means they get completed, but they’re not so good for unstables or harvesting.
One handy feature is that the nodes are identical for each shard, so if you jump up to a difficult to access artifact and collect it you can then shard hop to each of the other three and chances are you’ll find at least one more in the same place, the same being true for harvest nodes – I found a resource rich area and cleared it on Bloodiron and then did the same in each other shard, then back to Bloodiron to start again. This also works for mobs, so completing carnage quests or farming for cloth means you don’t have to hang around for respawns. I assume it works for clickable quest items too, will have to experiment, if so it’ll save some running round if you can trigger four from the same spot.