I made a post on my opinons about this a month or two ago. I'm ususally not a fan of wish list topics cause some monkey always comes in going "Necrons need +2 armor saves, and FnP... with WBB and power weapons, and Str 5 standard.. and Dreadnaughts.. cause Dreadnaughts are cool and I like Dreadnaughts, only with Railguns cause Railguns are cooler". I.E. the person has no understanding of balance, fluff or theme.. or concept.
Anyway my post wasnt a wish list but basically explained what I think Necrons need, a variety of troops, some sort of squad leader, Twin Linked Heavy Destroyers for the love of the Ctan please!