Originally Posted by ▀owser
Unbiased look at it:
-Blue Teams bot Lane is easier to gank. (because of added ganking routes through tri-bush)
-Purple Teams top is easier to gank. (because of added ganking routes through tri-bush)
However with a support+adc bot lane (designated warding done bot) ganks are more difficult to execute with success.
^ this gives an advantage to the purple side.
The other main layout advantages/disadvantages are the dragon and baron pits/coves/caves.
It is easier for the blue team to flash/jump/dash w/e over or through the wall near the dragon area to get in and out of that area quickly and safely. The Purple team has this same advantage in the Baron area.
There's also the layout of the buffs.
Shaco, Lee Sin, Dr. Mundo, and Shyvana all have a very easy time ganking top lane at level 2, before anyone buys any wards on purple, but on blue they are closer to bot, who probably started with wards.
Blue start Junglers have the same advantage on Blue side. Dem level 2 Alistar Ganks from the tribrush are pretty much guaranteed to burn a summoner's at least.
Purple can send an AP bot, which is very uncommon, and still give them blue.
Blue can send an AP top, which is very common, and still give them blue.
On bot blue has golems to take, to get them ahead of exp, and farm if the lane is too hot.
The same is true of top lane on purple, however, top can't take them when they spawn because he's a solo lane, so he doesn't start with a small exp advantage like blue side does.