The promised Fiesta ST vs. Clio R.S. mini comparison:
Both cars are very comparable - modern, turbocharged, with about the same power, quite "normal" from both outside and inside, full of modern technology etc. They both have great seats, good handling, enough torque whenever you ask for it etc.
Yet, Fiesta felt somehow less of a hot hatch than the Clio. I'll give a couple of examples:
The Engine: Fiesta's engine is certainly capable enough but it is just a standard EcoBoost engine and feels almost too polished for a hot hatch. Clio has a similarly spec'd engine but it feels more special and sounds is better (much better, IMO). This makes quite a difference in higher revs where in Clio, you have a nice sound that you will enjoy while the Fiesta feels like it's just noisy for no particularly good reason. Bad for longer trips on a motorway.
The Chassis: Fiesta's is stiff and quite uncomfortable in the city or on bumpy B-roads. That's not a criticism, many cars do that and I would accept it. But then you drive the Clio and wonder how they did that - I drove a Cup chassis and even that was very comfortable in low speeds while still allowing sporty ride in higher speeds. You can feel that in Renault Sport, they did something special to the suspension. In Ford, they have just lowered and stiffen it.
So, both cars are great but the Clio certainly felt more special, while the Fiesta felt "only" like a standard Fiesta with a strong engine and stiff suspension. Of course there are fundamental differences that you may not "forgive" the Clio like the AT but if you're fine with that, and the five doors (which I actually consider a plus), I think the Clio is a better car worth the higher price.