Which is better: an Incentive Stock Option (aka a statutory stock option) (an “ISO”) or a Nonqualified Stock Option (aka a Nonstatutory Stock Option) (an “NQO”)?

Many of our clients often ask: Which is better: an Incentive Stock Option (aka a statutory stock option) (an “ISO”) or a Nonqualified Stock Option (aka a Nonstatutory Stock Option) (an “NQO”)?  What are the differences between ISOs and NQOs?