The 'standard' NF-A15 PWM (140mm) and NF-F12 PWM (120mm), both with PWM control are fine for 99% of users.
The 'industrial' versions and other options bring a little more to the table - lower (or faster) RPM fans, different colours, slightly larger surface area - but Noctua do what they do well. Even their 'standard' fans are generally better than most competitors, without having to look at their more 'specialty' offerings.