So this is our experience, both of my girls still drink formula regularly, they are 5 and 3. No it's not out of a bottle...well the 3 year old does sometimes but anyway...
My older daughter said she likes the Chocolate toddler formula cold instead of hot (like chocolate milk). She said it tastes good but she prefers the taste of regular unflavored formula. My 3 year old "likes" the flavored formulas but won't go out of her way to ask for them. She too, prefers regular formula. Neither of them cared for the vanilla version. I've tried both as well, the vanilla tastes weird but the chocolate one is like Ovaltine or a chocolate vitamin shake.
Both girls do enjoy drinking Pediasures (as well as the off brands...same thing as the adult version Ensure). Basically a flavored vitamin drink that tastes best cold.
I'm sure any of the flavored formulas (just like Stage 2 formulas) have more sugar in them. It's to help the child adjust to the taste considering by the time they are drinking them, most children have vast tastebuds and don't care for bland drinks...unlike my girls though, they like the bland stuff!
But if you think of the overall benefits, a little extra sugar is okay. All the vitamins & nutrients by far outweigh a teaspoon or 2 of sugar...and in reality it's not much sugar as in juice boxes, popcicles or other 'treats'.
We will formula feed for as long as our kids will take it. The health benefits are amazing. All the vitamins & nutrients are worth the extra $20 a week per can. And really, formula is no different than an adult vitamin shake/drink, just less vitamins and geared toward tiny, growing bodies. Plus, it's far more healthy than cow's milk which offers the same amount of protein & D vitamins (if not less) than what is found in formula...and considering that cows milk is hard for even an adult stomach to digest (hence all the allergies, stomach & digestion problems out there) we prefer our girls to drink formula. They still eat dairy products but when it comes to drink of choice they prefer water, juice or formula (but they will drink cows milk but don't go out of their way to ask for it).
Anyway, that's my 2 cents. If she doesn't care for the flavored formulas, try Pediasures or just keep her on her regular Stage 2 (or stage 1) formula.