Build 1: Could be used in 3v3 or 5v5 and work, but not recommended if you expect to be fighting a mage in your lane, because someone like Malzahar, Annie, or Ryze can really mess you up early game if they know what they are doing.
Build 2: To be used if you expect to be fighting a mage in your lane.
Build 3: Used for soloing top in 5v5, the only problems you'll have up there would be against Caitlyn, Renekton, or Volibear. Buy wards if you can't help but push your lane pushing your lane, or if you feel you're going to be ganked anyway.

I was playing around with Wukong builds the moment I unlocked him, straight DPS didn't work, so I looked at what GuardsmanBob was doing on his stream, I saw Wriggle's Lantern and saw that Wukong needed to be tanky (although GuardsmanBob always buys a Wriggle's Lantern on every AD champion he plays, it still made sense to me.). You need to be adaptive as Wukong, and by that I mean picking your boots wisely. Sometimes, I buy Ninja Tabi, almost exclusively against Lee, Tryndamere, and Master Yi, though. I buy Mercury's Treads almost any other time otherwise (unless the other team has no AP champions and has 1 or 2 minor CC spells). With an opposing team like Kennen, Mordekaiser, Soraka, Xin Zhao, and Leona, get Mercury's Treads. Against a team like Pantheon, Master Yi, Garen, Nidalee, and Rammus, you should probably get Ninja Tabi.
Sell your Wriggle's (if you bought one) when you are done with your build and get a Bloodthirster. More lifesteal, damage, 23 armor isn't much late game, and you probably wont need a ward anymore.

I chose ignite for damage that synchronizes, as casting it while in your spinning state doesn't stop the spinning. Your ultimate, Cyclone, which will melt casters and fellow DPS carries. Utilize it best when they have about half health you Nimbus Strike toward them, you hit them with your Q, and then you Cyclone, knocking them up and doing a lot of damage. This is when you ignite them, when you actually run into them. Save this for team fights, where you can ignite the one being focused and knock every one up.
I chose flash because Wukong seems to be fun to gank and focus. Its also used well with your decoy, when they realize it isn't actually you they just exhausted and wasted their ultimate on, they will be even more blood-thirsty.

Whenever you are running through a jungle, or a bush in your lane, have you ever been scared because you think their whole team may be in it? Well that's why I hit W before I run into a suspicious bush, paranoid of ganks. They will attack the decoy, granted they were there to gank you, giving you time to run. They will have most likely come out of the bush to attack, so get in that bush and run for your life.

I've never done bad as a top soloing Wukong, and I mean that as serious and literally as possible. I've never gone below a 1.0 kill/death ratio, let alone a 1.0 kill/death/assist ratio as used in ranked stats.
Philosopher's Stone really isn't necessary, but seeing as you are solo top, you want to get ahead in levels as fast as possible, and Philosopher's Stone gives that perfect amount of sustainability with a little bonus, it'll pay itself back to you in 13 & 1/3 minutes with that 5 gold earned per 10 seconds passive.
Harass is very important if you want that lane domination, especially if they are someone ridiculously sustainable like Nasus. You'll have fun if you're against someone like Caitlyn (not the best solo, but I see them too often), Gangplank, Talon, Graves, and Pantheon.

Wukong is dwarfed by champions like Jax, Tryndamere, Udyr, Pantheon, Warwick, Lee Sin, and Garen (that's a long list) because of his passive, their is a higher chance the bonuses will be higher in a 5v5 than a 3v3, Another facter is his ultimate and Nimbus Strike. In a 5v5 there is a greater chance their team will be clumped together, thus a higher chance of hitting more people at once with Cyclone and a higher chance at hitting 3 people with nimbus strike. I use Wukong all the time in 3v3, but he's not as good as he could be in 5v5. If you are going to play him in 3v3, I recommend build 1, even though all these builds are all too similar.