The mk2/2.5 ST has a very good loyal following for several reasons.
Obviously you get the usual benefits of a hatchback over a dedicated sports etc, then it's got a pretty fine handling chassis straight out of the box.
Main pull for a lot of people though is the engine - the 2.5L turbo has a definite character all of it's own making lots of nice grumbly growly noises and delivering a really smooth flexible drive without having to flog the car through the gears. Loads of nice smooth torque in pretty much every gear
And that's before getting carried away with remaps and such like if that's your thing.
Downsides - they're a bit thirsty, fuel computer says I usually get mid to high 20's for day to day bimbling about, and not the most nimble of cars for throwing through the twisties due to the big heavy lump up front!
Looking at your car history - I'd say an ST is a lot more civilised & refined than a Type-R, a lot more grown-up interior wise than a VXR and handling is a lot less of a handful. Not much experience of the others to comment fairly. You also get a lot of car for your money.
No issues with people having the orange versions, each to their own. Just bear in mind it's a bit more of a challenge for some paintshops to get as good match in the event of any repairs needed.
Think the main differences between ST2 and ST3 is the 3 gets leather seats and trim inside plus higher spec sound system. 2010.25MY onwards the ST3 came standard with more options - auto wipers/headlights, privacy glass and suchlike. Think Ford dropped the ST1 by then too. Don't follow used prices but would think you could find a decent late ST3 for your budget?
I'm on my second ST now and there's nothing out there at the moment which would tempt me to let this one go.