Would personally recommend recruiting artilleries as they take less time and not much of difference b/w assassins and artilleries depending on their other stats such as Gold, Time Taken and attack power.
Using some simple maths,
Time for 1 artillery = 12 seconds
Artilleries per minute = 60/12 = 5
Attack power = 5*90 = 450
Time for 1 assassin = 1 minute
Attack power = 1 * 150 = 150
Therefore, it's proven that in early game, artillery's are worth more than assassins. When you're starting out, you need to quickly get troops and resources, waiting around for assassins isn't the best. Ofcourse it's going to cost more gold, but they're worth it. Food isn't a problem as they'll get wiped out instantly