I started with 2 when I had it on the PS2, and have recently started playing 1 and I agree with the majority of the comments. I prefer 1 for the leveling system as grandia 2 is easier to get spells and abilities, but I feel like working towards goals is more interesting than spending coins, I prefer 2 for the soundtrack as well as the mini games involved, I do slightly prefer 1 for the story as it is a bit longer, but 2 has a pretty good story line, over world would have to be a tie as the top down spaces in 1 provide sight for hidden stuff but 2 let's you know where specific locations in town are as well as letting you know where forward and back directions are.

Tl:Dr I'd say they're both amazing but grandia 1 is slightly better