well, first of all what mountain bike do you ride? a mtb with slicks can be great for city life, but if your bike is a piece of superstore garbage then you might be better suited with a nicer mountain bike. just throw slicks on it (schwalbe big apples seem popular). I have a friend that rides faster on his cheap mountain bike than on the fixed gear i loaned him.

flats/risers are nice for commuting. keeps you higher up to see traffic better. My favorite commuting bars are bullhorns. arguably i dislike drops the most (though with brake hoods they're not bad). you can always put bar ends on your flats/risers to give an extra hand position.

the kona and charge are comparable, relaxed road geo that will probably feel better to someone coming from a mountain bike (compared to more aggressive "track" geo). iirc the charge has kind of a low bottom bracket, so maybe the kona is better? thats only a concern if you're riding fixed.

see what you can give some test rides first though to see if this is something you want to pursue.