Just a guess on my part but I think the majority of people would prefer any of the other parks... for one simple reason:

More "Thrill" rides. Disneyland rides are 'theme' oriented rather than 'Thrill' oriented. For my family:

We prefer the 'theme' rides to the 'thrill' rides. Part of that is because all of my family has ridden those thrills rides... plus skydived, bungy jumped.... the 'thrill' is not a big deal for us. Been there done that, (for us).

Also - (I'm going to trigger Ramgator here) - Disneyland is ludicrously expensive. And it's not just the park entry fee.. everything at Disneyland - food, drink, etc is ludicrously priced.

So with that said...Disneyland is tradition for us. I first visited Disneyland two weeks after it first opened... I was 7 years old. We've been going ever since... at least once a year. Some years we went as many as 6 or 7 times! Allow me a quick anecdote to explain that 'tradition'.

The Tiki Room in Disneyland was my Dad and Mom's favorite...it's not a 'ride'. When I go to the Tiki Room these days it's the 'closest' I ever feel to my Dad and Mom, in heaven. And it's not only me who feel that... it's my kids who all knew their grandparents well... and also my oldest grandson (the only grandchild I had that can remember them).

All my family when we enter the Tiki Room do so "For Dad and Mom, Grandpa and Grandma, Great Grandpa and Great Grandma".... my parents. - JamesJM