I am currently nearing the end (or so it feels) of Phantasy Star 4. The only grinding I have done is accidental, as a result of exploration (nothing amazing, but better than average for a JRPG, with the possibility to visit towns earlier than the plot demands (and getting some harder battles)). Without grinding, the combat can be challenging at times (in a 'just right' way), though there are trash encounters too (helped by the macro system, which can be used to prepare combination attacks). The main plus of Phantasy Star 4, though, is that it is
fast: the normal movement speed on the world map and in town is just a bit slower than the running speed in Chrono Trigger (though there is no running in Phantasy Star 4) and much faster than the snail's pace of Fina Fantasy 6; also, though all attacks by player characters and enemies are animated, the animations are rather quick, so there is much less time wasted watching stuff happen, compared with other JRPGs (which is good, as random encounters are frequent).
Phantasy Star 4 is also fast in another important way: the plot. I got frustrated by the low 'density' of the plot in Final Fantasy 6 (lots of walking around, slowly, with nothing much happening), but in Phantasy Star 4 there is usually something interesting going on, with transport between planets an artifical satellites in addition to overland travel, with plenty of plot twists, attacks on the party and othe complications coming up. The setting is also pretty interesting -- it is almost mature, even! It is a solar-system-wide post-apocalypse with abandoned robots and spaceships lying around, alien characters and genetically engineered people. And magic, just because.
And the characters aren't annoying. he main annoyance is remembering (or working out) what the spells and abilities do, as there are no tooltip descriptions for them (some of them are explained in the manual). So, in short, I would recommend Phantasy Star 4. It is the best JRPG I have played so far. There is very little bullshit.
Chrono Trigger is decent all-around. It contains quite a few cool things. I would prefer it if it was not quite so targeted at children, and if the motivation was a little stronger (though perhaps I misremember it). The battle system is decent, with nice combination attacks, but suffers from having an "Active Time Battle" system -- i.e. wait for a while before you get to take your turn, every turn (without even enemy attack animations, necessarily). As far as I am concerned, making the player wait (with no thinking or new information) is a terrible sin for a game.
Golden Sun 1 and 2 have some interesting environments (including a giant tree one climbs that is also an enemy boss), puzzles that change the pace nicely and a decent purely turn-based combat system. I like the music, too.
The standard RPGCodex recommendation would be Anachronox, but I watched the film version as I could not stand the combat system, nor the terribly slow walking speed and transition animations (10 seconds for every lift, every time) combined with backtracking. It really would benefit from a source port or mod that sped everything up.
I have not gone far into Sigma Star Saga, but it is interesting as its battle system is a side-scrolling shooter. It is rather silly, though.
Final Fantasy 10 has a good combat system, but most of the rest of it is horrible. The premise of a water dominated world with a lot of swimming may have been done better by a different company -- that is, there are some interesting bits, but most of it, including the story and all of the player characters and villains, is schlock.
I find Final Fantasy 6 overrated, with slow walking, slow battles with a lot of waiting ("Active Time Battle", plus a character whose special attack involves waiting
) and whimsically abstract elements (in a bad way, including a character whose attacks involve gambling(!!)). The story is also nothing special (essentially the same sort of themes my ten-year-old self would make-believe, but I am now an adult). It may be that I was unreasonably impatient at the time (earlier this year) when I played this, though.