In TBC...the Alliance went to Outland. Draenei lore kinda got shelved as the race largely went neutral - probably because they was the likely original intent. There were strong BElf and Orc stories. NElfs got shoved in via the (again neutral) Cenarion Expedition. Illidan and the Naga were there with their own story. The big winners here were the BElfs with plenty of story involving them and KT, followed by the Orcs who got little things like Garrosh and Thrall returning home. The big Alliance story was....any help?
In LK...both sides had strong stories. The Alliance had an edge here IMO because Blizzard played up Arthas more than NZ. Even then, a big complaint here was how the HElfs got more story, more development than the other Alliance races combined. A lot of "Alliance" lore was actually AC or KT lore. It was stupid, but it was still AC lore. Lots of development for the Forsaken, BElfs again got some development through the Sunreavers, Garrosh and his impact on Orckind as well and we got to explore the origins of Dwarves/Gnomes and Humans. In terms of balance, LK probably wins out with the Alliance getting a slight edge due to Arthas instead of NZ.
In Cata and MoP....no question. Massive development and progression of Horde storylines. The Alliance is depicted poorly to make the Horde look good, Alliance lore was cut, Alliance stories shoehorned into Horde stories irrespective of how nonsensical such systems were. There is a distinct lack of quality and direction with the Alliance and the overall tone is dismal. Things picked up in MoP, but even then, massive problems exist.
Moving into WoD? We are seeing - YET AGAIN - a strong Orc centric story. We are also getting a Draenei story - but one which doesn't progress or advance the characters we know, nor does it progress or advance any of the stories OUR Draenei are involved with. We don't get to see their progress in the Hinterlandx, or their work with the Broken. We don't see them fight the Legion. We don't get to see them deal with the issue of Argus or see them repair the Exodar or build up Forest Song.
Regardless of whether you think C, TBC and LK were continuations of the WC3 campaigns -and they were - as far as story and progression and development of the actual factions is concerned, the Alliance need a boost. There hasn't really been an Alliance centric story since Vanilla. The Horde has had three - the BElfs, Orcs and Forsaken have all had a fair degree of development and progression. As have the Trolls (albeit, sporadically) and while the Goblins haven't had much development, their story came to a natural end with Azshara, with threads that can be picked up anytime and they have a place, role and presence within the Horde.
Alliance lore is generic, bland, underdeveloped (if at all) and written more to progress the Horde story than it is to progress their own.