Well, if you're considering Ni No Kuni, I assume you have a PS3. In which case I assume you have access to PSN, from which all my personal favourite JRPGs are readily available for mere pocket change!
For starters:
Grandia. The original. An epic adventure, comical and light-hearted, but still more than capable of being genuinely suspenseful or sad when the situation calls for it. The characters are well written, tend to stay clear of the most worn-out stereotypes, and you will greatly enjoy exploring the massive and richly varied world with them. The graphics will look a bit odd to modern eyes, but give the game a chance and you'll be used to this within the first hour! (Incidentally, some of the cutscenes are done anime-style!)
Originality be damned, no recommendation-list of mine is complete without
Final Fantasy IX! This and FF VI are pretty much tied for "Best FF Ever" (especially since the FF VII-buzz finally seems to be dying down after 17 years), but my money's on IX. This was the PENULTIMATE FF game - the last ever made with most of the original crew. They all wanted to commemorate this event by creating an epic game which would serve as a tribute to the entire preceding pantheon of Final Fantasies as well as a lasting monument to their talent. Everybody involved pulled out all the stops, most notably composer Nobuo Uematsu whose magnificent music had accompanied every single FF up to this point - here, he delivers what is widely regarded as his very finest work!
Finally, another recurring recommendation:
The Legend of Dragoon! This game has taken its share of flak for extreme lack of originality, which is not entirely unfounded - you know those cliches that seem to crop up somewhere in every single game of this kind? The stoic but kind-hearted swordsman, the vapid healer/love interest/childhood friend of the hero, the mysterious woman with an unknown past? The desert town, the fortress town, the snow town? The soap-operatic plot twists? Yup, Legend of Dragoon is pretty much put together entirely of those.
However, it is very WELL put together none the less, and if you give it a chance, you are pretty much sure to find SOMETHING to enjoy - the battle system is smooth and intuitive, the story is refreshingly fast-paced, the world is HUGE, and even though the playable characters are basically a lineup of every stereotype in the book, they do constitute a large and diverse group - and there is actual, tangible team spirit between them. They're a sympathetic and fun bunch.
Besides, if you're new to JRPGs, these cliches will likely seem somewhat fresher to you than they did to most of us! (And even if they don't: Most of the stuff which appears in LoD has often been done before - but it has very rarely been done BETTER!)