I chose Imperial Soldiers. First, they are legal army, often supported directly by King and Queen.
Secondly, even you think Pirates don't obey anyone's command, actually don't forget that there is Captain on each ship. Pirates often are not united, they don't like each other, they are together and team up only for their own sake, money, diamonds and whatever. They are ready to kill themselves if necessary. Imperial Soldiers are in law's side which means that they must like each other, even if don't, but however they have to work together, because its their military job.
Also, usually punishment for cached pirate is none less than death. I think you would chose to be more alive comparing to life where you can day any moment for any reason. Soldiers got supplies, food and arms legally, but pirates had to steal which is a bit risky.
Also in past, even here in Lego pirates you will notice that Soldiers are (logically) better armed than pirates. Look first in small sets, in Pirate Survival that shipwrecked pirate has only his pistol/gun, and some accessories as weapons as stick and equipment for digging. Look at Soldier's Arsenal. he is armed with gun, rifle, two swords, bag.... Look at Cannon Battle. This pirates has a gun, but Soldier has a shooting Cannon. In Kraken Attack, Pirates have sword and rifle, not bad at all! In Loot Island pirates have sword, gun and catapult, Soldier has shooting Cannon attached on his small boat! In Shipwreck Hideout Pirates are finally better armed than Soldiers. They have finally shooting Cannon, swords and rifles, Soldiers have only rifle and sword. But in Soldiers Fort, of course Imperials are better armed with Cannon, gun, Swords, but Pirate Captain is also nice armored in his boat with Dynamite and rifle and second pirate with sword. But Pirate's Brickbeard's Bounty is also well armored with Cannon, rifles, swords... in Advent Calendar also Soldiers got Rifle and gun, Pirates just a telescope and sword.
An the final word awesome Imperial Flahsip is heavy armored with few cannons, rifles, swords!
hehe yeah all the time in comics and sets Lego preferred Pirates as winners mostly! But the final word have Soldiers in last set Imperial Flagship (I really hope it is a joke and it will not be last, we will see pirates soon), so Imperials finally cough Pitate's Captian and won pirates! As mostly of you said, Soldiers always win hehe!
However, this was only my text, don't forget after all each side has it's advantages and disadvantages and what is the most important everyone has his own taste, and there is nothing to say against it!
My taste are Soldiers, I like Pirates lot, but Soldiers little more.
