RSUs are better but you can't get them before a company goes public. RSUs will have non-zero value. Options might never be exercisable but they're the normal way you get a stake of ownership at a startup (you don't get stock). So if you want to own part of a company before it goes public and you're not an investor, options are usually the only way on offer.
You can certainly get RSUs in a company before it goes public. You won't (generally) be able to sell them very easily, but being a publicly traded is not a requirement for issuing stock to employees.
