So, I think the problem here (and the reason people are downvoting) is you're asking the wrong question. If you were a Professional player, then you'd have multiple builds for each map/matchup combination so as to be unpredictable. If you were an Amateur player, then it doesn't really matter which build you choose, picking one and sticking with it is the best you can do to get ahead.
Most importantly, you should know your build by the loading screen.
Its a fairly easy mistake to make, you get in a match and you scout your opponent and you try to radically shift your build. In fact, its a mistake even pro players like TLO, Day9 and iNcontroL make. You see an opportunity and you try and adapt some other build, that you have practiced a couple times, but haven't ironed out yet, and you get eaten alive. Actually, let me tell you a story:
A Story about Tzenes
I played in a tournament rather recently and I got matched up in the round of 16 against a Terran player in a Bo3. Going into this my plan was simple: Game 1 I'll do some rush, try to catch him off guard plus make him think I'm bad, then settle into a more standard Game 2 and 3. So Game 1 I pull a 7 Roach Rush (yes I think its a bad build, but I wanted him to think I was bad), and I just out Micro him. Game 2 I settle into my more standard 15 hatch, I expand to 6 bases to his 3, but he manages to get a key drop off and catch all my Broodlords, mows through my not yet morphed Banelings, split the map and forces an early GG. So now I come to Metalopolis for Game 3.
Now I hate Metalopolis as Zerg, I think it is my worst map for ZvT, I think the thing is horribly unbalanced unless you can get cross positions, and even then its hard to stop a Terran from splitting the map. Going in to this, my plan is: 15 expand -> early Roaches -> Roach/Hydra drop -> Muta. So we spawn and sure enough its close positions, so I send out an early Drone scout (10) in case he's rushing, and I see he hasn't walled off yet. Not only that, but I manage to micro my Drone so he places his Rax out of position, there is a hole big enough to drive an Infestor through sideways. So I see I'm at 15 Drones, 200 Minerals, and I go screw this 15 Pool, 14 Gas, SPEEDLINGS!
Remember how I said you shouldn't switch plans half way through the game? Well, sure enough by the time me first 10 lings pop, ling speed isn't finished (normally its 14 Gas, 14 Pool so it finishes at the same time), so by the time they get to his base, he's thrown up 2 more Rax and safely walled himself off. Ouch. So now I have to fall back on my original plan of Roach/Hydra, except I don't have my Roach Warren down, my Expo is half done, and all I've got for defense is 10 lings (and he's looking ready to move out. So I throw down a Spine Crawler, demonstrate superior control, and hold off his initial push. Except, by now he's expanded and is throwing down a Starport, and I don't even have my Lair yet.
I won't bore you with the rest of the match but its a long row of me being behind and trying to hold on, till I finally tap out to be done with it.
So here's the moral of the story boys and girls: "Don't switch your horses mid stream."