The choice of aircraft is always political. The replacement for the Chippy and Bulldog in the JEFTS contract was always going to be about the total package and not just the aircraft. The T67 probably would not have been the choice had it been based on aircraft alone. Mind you, I'm not sure how Huntings became the choice of provider, except on price.
The JP replacement was specified as a turboprop - there were only ever going to be 2 contenders. The choice was political and in the end, I don't think it was a bad one. By the time I got to fly the Tucano, most of the issues had been sorted out (we were up to the Mk16 version of the Engine Electronic Control!) and in the end, the RAF ended up with a good training aircraft. It's certainly better than the JP, and from my few flights in a PC9, I get the impression there is little to chose between them - except that I consider the Tuc to be a slightly better training environment - particularly compared to the Swiss built PC9s with their engine control.
Had the procurers listened to the RAF, we would have probably ended up with something like the S211.
Speaking of the political procurement of the Tucano, the aircraft were built my Short's mostly Roman Catholic workforce and when the aircraft were delivered from the factory, they were left on a remote stand on the other side of the airfield for four weeks just in case they had a bomb built into them! (The longest duration timer available to the IRA was 28 days allegedly!