Over the course of her life, Ororo Monroe has been trained as a juvenile thief, worshiped as a goddess, and hated as a mutant. Since Charles Xavier enlisted her to join the X-Men, Storm has grown as a warrior and as a leader.Marvel Source
Her control over the climate has been honed through constant training and numerous battles, and her arsenal of elemental powers, from shattering lightning strikes to freezing winds, make her a force of nature to be feared and respected.
Chain lightning is not flagged as area so it doesn't benefit from any of your +area damage gear. It is also severely weaker against single targets, whereas Ball Lightning is equally good against hordes of mobs as it is against bosses. The clear winner is Ball Lightning.
Medallion - I like the Doc Oc one the best, but I am also playing with the new Cosmic Pyro medallion to see if it is better. Doom is a good third choice.
Uru - Ranged is the clear choice here. Especially if you use Crashing Hail since it is a physical attack and not energy. All of your energy attacks are also ranged so it works great.
Artifacts - You could throw the Advanced Metasensory one if you want but the above is my preference.
Powers -
To me Chain Lightning and Ball lightning are almost interchangeable. It just all depends on which one you like more. Ball lightning does more damage on single targets but is slower. Chain Lightning hits more mobs that are farther away.
Also I think that Quickening Breeze and Refreshing Breeze are both good. Once raids start I will probably switch to Refreshing for the group benefit.
Ultimate Powers - Goddess of Weather is probably the strongest Ultimate in the game and is likely to get nerfed. On level one you can throw it down and a few AOE's and destroy 4 bosses at a time in Midtown Manhattan. It also wipes out Doombots on X-Def. At level 4 you can drop it and go afk and come back and pick up your loots!
Gear - I will edit this later as I do more testing. Any advice is appreciated.