Destiny of an Emperor. It is, by far, the greatest RPG ever made for the NES. I highly suggest checking it out. Although most people would disagree with me when I label it as such, the majority, if not all, of the people who have played this game, would agree that it is amazing. Ancient China ftw.

Also for the NES, although not as suggested because chances are you will not enjoy it as much, is Wizardry: Proving Grounds of the Mad Overlord. It is a hardcore dungeon crawler with very minimal graphic capability. The storyline is decent, when there is one. The main feature of the game is the difficulty. There is no power leveling. You can pretty much die at any level. It is fun!

SNES has Wizardry V: Heart of the Maelstrom, which is also suggested and has slightly, emphasis on the word, improved graphics. The difficulty is about the same. Both games also feature a lot of running around and puzzle solving. Again, a dungeon crawler to the very core.

Robo Trek is a mildly difficult but mostly fun game for the SNES. You build robots to fight for you! Any game with customizable robots as party members is automatically fun.

Lufia & The Fortress of Doom and Lufia 2: Rise of the Sinistrals are also highly recommended SNES games. Both games are fairly difficult but not overly so and both feature pretty neat puzzles. I would suggest the latter game, simply because it is a smoother experience gameplay-wise.

Back to NES for a brief minute so I can suggest, although very limitly because the game is fun but can be a bit hard to handle for most people: Innuendo: Way of the Ninja.

I'm suggesting the aforementioned Breath of Fire games, although the first two (both of SNES) are drastically superior to the third and fourth, in my opinion.

Also Suikoden, although good luck finding the first two games (Playstation) for a reasonable price. The third game is decent, fourth game is viewed as the worst in the series, and the fifth game is enjoyable (although I still haven't completed it). Tactics is eh, but I've never really gotten along with most strategy games.

Er.. yay suggestions!