Thats all well and good, but I'm not sure the other teams were doing that as consistently as the West Indies were. Lost series, either home or away were extremely, extremely rare for the West Indies in the earlier part of that period and I don't think that any other team can match them in that regard.
OK, let's consider Pakistan. Their most impressive period was 1982\83-1988\89:
Home to Australia, 1982\83: 3-0 whitewash
Home to India, 1982\83: won 3-0
Away in India, 1983\84:drew 0-0
Away in Australia, 1983\84: lost 0-2
Home to England, 1983\84: won 1-0
Home to India, 1984\85: drew 0-0 (just 2 Tests)
Home to New Zealand, 1984\85: won 2-0
Away in New Zealand, 1984\85: lost 0-2
Home to Sri Lanka, 1985\86: won 2-0
Away in Sri Lanka, 1985\86: drew 1-1
Home to West Indies, 1986\87: drew 1-1
Away in India, 1986\87: won 1-0
Away in England, 1987: won 1-0
Home to England, 1987\88: won 1-0
Away in West Indies, 1988: drew 1-1
Home to Australia, 1988\89: won 1-0
Away in New Zealand, 1988\89: drew 0-0
Really, the only blemish on that record is the loss in Australia (and that'd probably have been the other way around had it been a year later), the failure to win in Sri Lanka and the earlier loss in New Zealand. Really, I don't think you can conclusively split them and West Indies after 1986. They even managed what West Indies did not, and won in India.
The WI were never challenged in that period by NZ.
86/87 season to end 1989 they won 2 Tests out of 16 and their team bowling average was 37
. Its hardly the stuff of champions and that records worse than the supposedly current crappy England team
Now let's consider New Zealand from a year later:
Home to England, 1983\84: won 1-0
Home to Sri Lanka, 1983\84: won 2-0
Away in Pakistan, 1984\85: lost 0-2
Home to Pakistan, 1984\85: won 2-0
Away in West Indies, 1984\85: lost 0-2
Away in Australia, 1985\86: won 2-1
Home to Australia, 1985\86: won 1-0
Away in England, 1986: won 1-0
Home to West Indies, 1986\87: drew 1-1
Away in Australia, 1987\88: lost 0-1 (should have been a 1-1 draw)
Home to England, 1987\88: drew 0-0
Away in India, 1988\89: lost 1-2
Home to Pakistan, 1988\89: drew 0-0
One-off Test in Australia: draw
Home to India, 1989\90: won 1-0
One-off Test at home to Australia: win
This record has a tad more blemishes on it than West Indies or Pakistan, those being the 3 in a row of defeat in Australia, failure to beat England at home, and loss in India.
India, incidentally, at the same time were their usual selves; usually a handful at home, usually utterly anodyne away. England and Australia were both a shambles.
Overall, I'd really say there was little to divide West Indies, Pakistan and New Zealand at the top of the pile after the watershed point (for West Indies alone) of summer 1986.