Tactics. Tactics. Tactics.
Instead of the Standard Melodramatic FF Plot with no extra themes (most FFs), or the Standard Melodramatic FF Plot upgraded with the cliche theme of technology versus magic (FFVI and FFVII), it has something that *could* be the Standard Melodramatic FF Plot after exposure to such massive amounts of power politics and crazy socioreligious themes that the "Standard" and Melodramatic" parts have been completely dissolved. It didn't even bother with a romantic interest for Ramza, because there were bigger metaphorical fish for the plot to fry.
And the battle system. Oh, the battle system. This is what really set it apart. No other FF is regularly capable of delivering an actual challenge. Not only do you tend to find yourself outnumbered and outflanked as the game goes on, but the AI is actually good enough to take advantage of that instead of just charging down to get chumped. Whereas it was pretty easy to come out of encounters unharmed in numbered FFs, Tactics left players beaten and bloody at the end of each battle. You don't play FFT, you survive it.
Add the best soundtrack of any FF besides VI, and it's easy to see why FF Tactics should be at the top of everyone's list.
