I've got both sitting beside each other. Right now my JP isn't running, but at a normal party at my house with around 12 people, half adults and half kids 7-14, the JP wins hands down. The girls and boys like it equally. LAH also gets quite a bit of love for the crane and magnets, but they're just not as familiar with the movie and therefore the modes aren't as easy to follow. Everyone knows what a stampede is, but not everyone understands the scenes from a movie that was made before they were born.
They're sister machines, share the same sounds, Smart Missle, shaker motor, mode gameplay, etc so they are going to play somewhat similar. Layout-wise they aren't the same of course, but if you are familiar with how one works, you'll quickly feel at home on the other.
JP seems to be a little easier to find, although still not common. I had to have mind shipped in from across the country. JP also goes for a little more money, which is probably due to the wider appeal of the theme. And of course with the new Jurassic Park movies coming out, I assume that dinos will once again be a hot item.
This may be a little more help for LAH:
https://pinside.com/pinball/forum/topic/opinions-of-lah
You probably can't go wrong either way. Good luck!