I have Sora 8spd with the thumb-lever, and I love them. I have not owned a bike with the 105+ paddle-style brifters, but I have tried them out on a friend's bike, and I was not impressed that the design is inherently better. I like how the opposite directions of the brifter-lever vs thumb-lever help my intuition of whether I'm "pushing up the gears" vs "slipping down the gears" with the derailleur (just like mtn trigger shifters are on opposite sides of the handlebars and worked by thumb vs fingers).

Is the advantage of the paddle-style just that you can reach all the controls from drops and tops?