When you're giving your opinion but don't want to say it too strongly (because you're being polite or because you don't feel strongly about it), you can say "I would ___". Examples of this are:
I would say that one's probably a little better than this one.
I would go with the higher-priced model.
You often use "I would ___" when you're giving someone else advice, and you're not the person making the final decision. For example, if your friend asks you for advice, you can answer with "I would ___".