The generalisation with Bulgarian wine is that it has a pretty good flavour and an excellent price but it doesn't "burn clean"
I seem to get more of a hangover with Bulgarian stuff
The least hangover-ish stuff is german dry riesling. Mrs Vorspung has a low tolerance these days to wine the night before but reports some success with Prosecco
The South African wine seems better at the low price point than the Oz stuff. For example Coop do a generic South African Red wine that is unexciting but quite glugable. Back in the 80s I used to live in London and got a bottle of wine most nights from the wine shop
The best stuff I used to get then was red austrailian with a picture of a duck on it for a fiver. Maybe even less than a fiver, I don't remember exactly. Utterly fantastic