Most Helpful Girl
I'd say whatever makes you feel the most confident. In my opinion, to look their best every woman should dress for their shape, whether they're tall and slim, have some curves, or are bigger. Finding what's right to suit your body is key. Meaning it highlights your best features, and plays down those that you aren't so comfortable with. Personally, I think a nice dress that hugs your chest area and is kind of "flowy" and loose towards your stomach would look really nice. With your skin color, I don't know why but I automatically picture a pink polkadot dress. But again, which ever makes you feel the most confident is what you should go for, when you look good, you feel good, and vice versa.
Most Helpful Guy
If you are the actual definition of chubby, you can pull off the usual clothing girls wear and your curves will augment your femininity. I've never seen a chubby girl and thought she needed to dress a certain way because of her weight.
Now, if you're obese? That's a little different. Dark colors will flatter you more and you'll need to accept that some people won't like your legs and gut. Some people won't mind at all.
Personally, a girl in yoga pants does me in. If you're going to show your legs, have proper footwear that shows your ankles so we get the full show. Jeans are neutral, can't go wrong there. None of these preferences change whether you're fit or chubby.