I've not been to Europapark but I have been to both the Disney parks in Tokyo.
I'd recommend Port Aventura in Salou near Barcelona in Spain, particularly if you can go in the off season and get a hotel deal (you don't need to go to an 'official' partner hotel as there are lots of nearby alternatives.)
Landscaping is lovely, some of the shows can be world class and a few of the thrill rides are much more 'thrilling' than those at the Tokyo Disney Parks (more at the level of that roller coaster that runs through a building in Kamakura Amusement Park in central Tokyo.)
Getting to Salou shouldn't be hugely expensive as you can get there relatively easily from Reus, Barcelona and even Girona airports. It's by the sea, there's Club Caribe next door for water attractions and there are other cities and towns to be explored near by. Worth considering if you haven't already. My own daughter LOVED the Tokyo Disney Parks but there was an awful lot she could go on as a 90cm tall child. I'll have to wait until she's considerably taller to take her to Port Aventura.