Traveling with 4 18 year olds, wants to buy extended day passes, either 4 or 5 day hopper passes, or the universal pass, pay for two days, use for 5, something like that. Anyway, where would my teens have more fun, which parks Thanks.
If they really like roller coasters and stuff they'll probably like Universal. But, WDW has a huge amount of stuff, whereas Universal has 2 parks and not so much stuff. A lot of people will argue with me I'm sure. I personally hated Universal and IOA when we were there this winter. I was bored, and well, disgusted with the place. I'm 17 if that helps. But a lot of my friends like Universal and IOA better than WDW, or about the same as WDW. It really depends on what they like. If they're not big roller coaster people go to WDW, because there is very little at Universal and IOA besides roller coasters.
My teens definately prefer Universal & Islands much more than Disney. They're at the age where I have to DRAG them to Disney. We usually spend 5 days at Universal and 1-2 days at WDW now. It all depends on what the teens enjoy. If they like thrill rides, they will LOVE the Universal parks. If not, then WDW will be more to their liking...
Universal is heavily into simulators and water rides and effects even though there are several shows too. There's really only three coasters (4 if you count both sides of Dueling Dragons and also one little coaster for the younger set. I suspect that the age you mentioned would likely enjoy Universal more but they would certainly enjoy either one IMO.
Just thought maybe you should go to both sights and get them to send you there free tapes and let the 18 yr olds watch them and decide for themselves. WE are not big ride kinda of family so my teens like Disney. We ride all the rides there and like the theming in all of them. Seems Universal is more like Cedar Pointe and we live in Ohio and do not do it often.