Are you actually talking about Pack n' Play No. 1 and not Pack n' Play No. 2?
If you -are- talking about No. 1, then it really depends on what size you prefer. Mark is thinner and shorter than No. 1. It also has a firm inner core unlike the No. 1 which only has a firm inner core in the base, but the shaft is all soft silicone.
If you actually mean No. 2, then they are almost the same size (according to the product description, I don't yet have them both to compare). It really depends on whether or not you want the firm inner core through the shaft or not.
I, personally, plan on getting both Mark and Pack n' Play No. 2.
Pack n' Play No. 1 most closely resembles The Vamp, which is way too big for me, so I'm not going to even attempt that one. Though the Pack n' Play -is- soft silicone where as The Vamp is completely made of firm silicone.