The "would" in this case is generally just a softening, polite word. Asked if you prefer coffee with milk or cream, you might respond, "I would prefer cream" only because it sounds more polite than "I prefer cream." However, both are correct, and neither is rude or impolite. Especially if you add a please or thank you after it!
It could mean that after some given situation or alternative, then you would prefer...
"If I had a choice of going to New York or Orlando, I would prefer Orlando."
- For Teachers