The question is - WHAT DO I REPLACE THE 156 WITH ?
A few ideas:-
pmp lives in australia, so the choice is a little more limited compared with the UK. for example, diesels are unheard of in anything more than a couple years old.
for reliability, i too recommend a Jap car, and like already recommended, i would shortlist:
*subaru liberty (same as legacy overseas); choice of 2.5, 3.0, and 2.5 turbo, sedan or wagon
*mazda6: hatch, sedan, wagon
*honda accord euro
can't go wrong with any of the above IF they have been properly-maintained with FSH and low km's. for an everyday car, i'd go the subaru or honda.
if you are happy to go with another alfa, then i recommend buying from an alfa dealer: which means 'warranty', or choose a demo model. they tend only to sell cars that they are happy to sell. that is, they have a reputation to uphold (NB: whilst not perfect, in australia, the dealers seem better than in the UK). the small premium you pay for a caryard alfa outweighs potential risks of a privately sold vehicle - can you vouch for that pmp?
my shortlist for an alfa would be:
*156 TS 5spd manual: never had any major probs with my '99 model, owned for 5+ yrs and to 160K km's; a 6spd manual 2.5 V6 would be the pick if you can find one
*GTA: 147 or 156; again, from a DEALER, not privately; BUDGET for the Q2 diff upgrade (refuse at your own peril)
*GT: 2.0 JTS or 3.2L V6
*159 2.2L JTS
as also discussed, it depends on your budget. but again, i would personally avoid a privately sold alfa unless you know the person, you know they have looked after it, and it has FSH.
i think you must have chosen poorly with the selespeed. i don't know the full story, but maybe it was too cheap to be true, without a FSH, and sold privately. all big no-no's.
at the end of the day, i think you have your own ideas, and probably aren't going to listen to a bunch of AO members behind computer screens, who aren't the ones paying.
just admit though, you bought a lemon (sorry to be a broken record), and you lost badly. it's not a true reflection on alfa's, as only a handful across the world (relatively speaking) have had such major issues like yours.