Does it matter what thread serger i buy?

Question:3, 4, or 5 thread? I've used an industrial one at school, however buying one is a different story. Which one?

Answers:
Well think of a few things, what you will use it for, how much cash you have to outlay for this, and what brands do you like. Such as White, Singer, Brother, ect.

My choice I like is always Singer, but basicly like when buying a sewing machine, what will you use it for?