I searched and searched for advice on speakers but it gave me a headache every time. I have no idea.
Went the safe route using halfrauds (actually cheapest) and ended up with pioneer TS-R1350S 13cm for the front (straight swap) and pioneer TS-R1051S 10cm for the rear.
I chose these due to having the best reviews of speakers with a faceplate that I knew I could fit.
The rears needed the holes enlarging as I had prefacelift 3" sspeakers. I did this with a dremmel cutting disc and a sanding adapter.
Really really happy with the outcome for £75 (at time of purchase), the clarity is a huge improvement but still lacks any bass.
I have also ordered a kenwood under seat sub with an inbuilt amp so should also be plug and play if I wire it to the HU. Obviously won't fit behind or under the seat so it may have to go in the passenger footwell. Trial and error.