What do you think is the most balanced and fun TT RPG?
If well-balanced is the goal, my suggestion would be Fate. I prefer Fate Core (or perhaps Fate Condensed although I've never tried it). Personally, I never really got on board with Fate Accelerated (the tendency for approach spamming left me with a bad taste in my mouth).
Fate is an elegant little system that can be used with any sort of tale. The default system works incredibly well on its own with no tweaks, but for the folks that have an urge ... there are tons of dials to twist if they are looking for something with a bit more heft/crunch/structure to it (supers, magic systems, etc).
As a narrative game, it does take a fair bit of getting used to if one is coming over from a more structured, physics-replicator type of tactical game, but the jump is worth the effort in my opinion.
I guess what I mean by that is if one plays a Fate game and expects it t be D&D ... they will walk away disappointed.
The SRD (for each of the versions) is online and incredibly easy to sift through, and the core book is very affordable as well (the developers suggest $5 but the 'pay what you like' option includes down to and including free if you prefer).