Can you suggest any other cars which suit the above post criteria?
Perhaps some other sort of warm hatch? I've no idea what your budget is because I don't know the specifics of your tradein but something like a Fiesta ST? It's different to a Polo.
The thing I'm struggling to get my head around is that both of these cars seem to be the same thing. One is just a slightly more modern version of the other. The performance between the two is broadly similar, not sure where the 2 second 0-60 difference comes from because it looks more like a 0.3 second difference.
I understand why you might be bored of the Polo GTI and feel its time to move on but I don't understand how fundamentally the same thing again would do anything other than satisfy the shiny-new-thing craving for a month until the novelty wears off and you realise it's just another 140-150bhp Polo again, the same as your last one. Only this time you've bought it new and it'll cost you thousands in depreciation to realise this.
So, if you are bored and fancy something new you must, in my opinion, either upgrade or move sideways to something different - the Fiesta lacks the quality of the Polo but more than makes up for it by being more chuckable and probably more fun. Perhaps thats whats missing from the Polo for you?
If all you want is more Polo then perhaps the best answer to the question is the car you already have an £10,000 spare to spend on petrol and holidays.
Specifically which Polo is it you have, what year is it?