The best vegetables are THE ONES YOU WILL EAT.
Having said that …
Potatoes and corn are, technically, starches even though they come from are plants. So you could eat too many of those. Otherwise, it’s hard to imagine over-consuming vegetables or getting too many calories from vegetables.
Green is good.
A variety of colors signals a variety of nutrients, to some degree.
Cooked is not necessarily worse than raw. Light cooking can increase the bio-availability of the nutrients you’re eating.
Eat the ones you will eat.