We did both last year...at HS. For the HS one, we bought for 4 of us for May as a surprise for my daughter and her boyfriend who were on a trip with us. We were staying at Riviera, but planned to do only the Universal parks because we all had APs to those parks.
So the After Hours was HS in May...and it was a rainy evening which may have helped thin crowds a bit, but it cleared up well enough by the time we arrive and we go there close to the early 7pm entry. The lines were a bit long for the ice cream/popcorn/drinks early on, at least in the Toy Story area, but they thinned later. We went early so we could do a quick dinner at Mama Melrose before our evening, so we weren't starving for the "free" snacks but we got our fill. We rode all that we wanted before midnight, and the best thing was our ride on a TOTALLY EMPTY Tower around the 11pm mark. We had the whole elevator to ourselves and we each sat in a corner.
Returned in September for the Sept 13th Moonlight Magic. We still did quite a bit, but the lines for food were much longer (since you had the vouchers for the other food) and since we had just been in May we weren't trying to do ALL the things. I think I actually preferred the paid event over the DVC one in that case.
Now we have been fortunate to do MM at Typhoon Lagoon, Magic Kingdom, and Animal Kingdom but no paid events there. MK was YEARS ago so hard to compare as it's different now. Typhoon Lagoon was super fun and we got to meet Elvis Stitch! AK was nice. I am HOPING to finally do an EPCOT MM event as we already had a trip planned for January when they announced the January event! If I can just ride Guardians over and over again for that event I'll be happy.