Went to most of these games - well, all of them except the infamous Millwall away match. My brother went to that one and still talks about it - usually mentioning that he's surprised he's still alive.
For numbers and all round chaos the '83 Pompey one is undoubtedly the worst, but the two games against Chelsea in 75/76 & 76/77 were actually more scary. I saw some evil poo on those days, like Chelsea fans picking on defenceless old(ish) blokes for no reason - Leeds in the eighties were bad but I think Chelsea in the seventies were worse. It was pretty hairy at Stamford Bridge as well - I saw the infamous axeman there.
The Charlton 'droogs' were scary for about thirty seconds for their shock value but ended up getting a right kicking once the brave lads in the Demport (having initially run away) realised there weren't that many of them.
The Watney Cup match against Stoke was also pretty bad, probably because it was, in all but name, a pre-season friendly and no-one was expecting it.
The Everton cup match was just about numbers and the times we were in.
And let's not forget that we had our moments too. I know that folks in Peterborough still talk about that day in 1975 which was, as it goes, disgusting (although I'm sure there are a few morons on here who still think it was good clean fun), but quite a few Saturday away games in the second half of that season saw our mob terrorising some poor unsuspecting town or other, albeit on a smaller scale. Blackburn (renamed Greenburn for a while) was the second in terms of scale, although at least they had a few 'lads' of their own, but trips to 'the likes of' Hereford, Bournemouth and Watford provided a few 'thrills and spills'. Away fans were still being put in the Lyndhurst in those days so there was quite a big crew of Argyle fans over there in readiness - I particularly remember some Crystal Palace (twice) and Blackpool fans looking as though they wished they'd stayed at home.
The promotion season in 85/86 had its moments as well, Wigan away being particularly 'memorable'.