All FFs have their no level challenge basically. FF8 was the only no level challenge I can do because it was just that easy XD; It's the only way to get max stats in FF8 anyway.
FF7 may not be worse than FF8 compare to "normal attack please" problem. At least in FF7 if you aren't overleveling, you DO need the magic to great length. FF8, minimal level challenge still requires no magic, not even cure (because you can easily leave Quistis at 1 hp to endlessly spam whatever blue magic you need. Limit break system is a lot better than the low hp special system in FF8 for how easily abusable Quistis and Squall is.)
Triple Triad is indeed fun, but I really hate the space laws in the space station =(
FF9 is fun because of its plot to me... its a really cute plot and there's really no screwup until they pull off necron to a "what are you talking about" scale. Again, the don't try too hard at super plot twist on the final boss applies to FF9 pretty well. Kuja is obviously a bad guy and basically is your final boss for a very, very long time.
FF2 I never played it... can't comment.
Didn't play FF6 on GBA either, except I heard of unlimited Illumina and Atma Weapon?