I'm a Sorcerer and have full sets of the following. What sets complement each other.
Burning spellweave
Necropotence
Mother's sorrow
Law of Julianos
Mantle of Siroria
There are ways to build to use otherwise, this is just the general wisdom limited purely to what you have:
PvE Damage: Mother's Sorrow/Julianos
PvP: Necropotence/Spellweave (maybe Julianos)
PvE Damage for situations you won't have to move much: Mother's Sorrow/Siroria
None of those are terrible sets. Though there are better ones out there you could work on getting.
Lots of changes happening November 1 for gear. You can wait until the dust settles a bit.
Currently, Mothers Sorrow should be your base set. Siroria is a strong set, but works best against stationary bosses you stack on. Burning Spellweave is good, but works better with a DK. Necro is pet sorc set, or a set you would typically wear in an arena like VMA where you need a lot of resources. Julianos is a reliable, strong set but one that will be outperformed by sets like Medusa, Spell Strategist, or even War Maiden, depending on your build.
Of all of those options, if I were running trials or dungeons, I'd probably go with Mother's Sorrow and Siroria because you get the 5% bump against those enemies
For vet content as dd, Siroria is the best set, mainly because minor slayer. Also, remember that you don't need to stand in the circle, but every few seconds you should run through it ;p
Then I would go for a Mother's Sorrow if you play more class based build or BSW if you make build for fire dmg (then BDV monster set would be nice addition).
Mythic:
Death Dealers Fete
Ring of the Pale Order (if you are doing hard-ish solo content or don't want to worry about or don't have the bar space for active healing)
Harpooner's Wading Kilt (will not be as good after next patch anymore, but still good for certain situations)
And if the dam breaks open many years too soon
And if there is no room upon the hill
And if your head explodes with dark forebodings too
I'll see you on the dark side of the moon
What gear should I be farming besides the Maelstorm staff.
I agree with @thorwyn and add Relequen into that mix. There is a lot of speculation that it will become the dominant DD set once the hybrid changes go into effect, but that has yet to be confirmed. As for monster sets, Kjalnar's NIghtmare is one to farm with Zaan or Maw.