Quality chocolate is a no-brainer, but not original. If you know your valentine well, candy can be very personal, creative and gratifying.
For the morning person / early bird: Chocolate-covered espresso beans
A personal favorite of mine. Right as the sugar buzz tapers, the coffee buzz kicks in. However, I am in no way a morning person. It's for anybody that likes coffee.
For the health freak: Fruit strips (a.k.a. fruit leather)
I just discovered fruit leather (they sell it at starbucks). Picture a Fruit Roll Up that tastes better and is made with 100% fruit. It's pretty good.
Another option could be taking some strawberry/fruit and lightly drizzling with syrup.
For the obsessive-compulsive: Jelly Beans... custom assorted
Many people who like jelly beans are particular about their flavors. Go to a candy shop that sells Jelly Belly beans separately, and leave out the flavors she/he dislikes. Your valentine will be impressed that you actually listen to their flavor nitpicking.
For the wine-o: Liquor-filled chocolates
Someone once asked me, while stuffing her face, "Mmmm is there anything better than chocolate filled with caramel?" to which I promptly replied "Yes. Chocolate filled with booze."
For the diabetic: Cannoli, cheesecake (low-sugar)
Okay, diabteic isn't a personality, and cheesecake isn't a candy. But this is my list and I can do what I want.
For the adventurous / free spirit: Marzipan
Once again, this almost crosses the line between candy and pastry. You can get mass-produced marzipan in most good candy stores (it's fairly popular). To get fresh made marzipan, you might have to track down an Italian bakery. Marzipan is a soft candy made from almond paste with a texture similar to a brownie. It's sweet (think DiSaronno Amaretto) and to me has a slight cherry flavor to it. A good gift for those with an aversion to the ordinary.
For the nostalgic man- or woman-child: RETRO candy
Every once in a while I see a candy form my childhood and get giddy and have to buy it. Now imagine someone stuck in the 1990s or '80s (or before!) -- multiply that feeling by 10. You might have to order it online or go to a specialty store to get it, but it could make their day.
The stoner: Hemp candy
Yes, they make lollipops, gummy bears, and various other things that taste like cannabis. I don't see how cannsbis would make a desirable food. But to each his own.
For the chocolate lover: Fudge
This may seem obvious, but I wouldn't be suprised if I asked 100 people what to get a chocolate lover and less than half said fudge. And it's not just everywhere you see hand-made fudge shops. The chocolate lover's tolerance is pretty high, so it would take something decadent like a gourmet candy to get them excited. A fudge shop is also usually a mecca for other creative chocolate concoctions. Fudge FTW.