Pro Longwear has 16 shades, and Select Cover-Up has 13 according to the UK website.
Overall, I don't have a preference as I use them for different purposes. If you're going for more of a polished look and complete cover I'd go for Pro Longwear, but if you want a very natural looking concealer with good coverage go for Select Cover-Up. Both are buildable for the desired look. If Pro Longwear has a better dispenser I might have swung towards it, but it's such a pet peeve of mine!
I hope this helps find the perfect Mac concealer. I'll post looks with both of them soon with a more in depth review of them individually so keep an eye on my Twitter for when that's up!
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