As with wine, the most expensive is not necessarily the best, and it's all down to personal taste.
I'm not particularly bothered about older variants, and like nothing more than a night in front of the fire with a good 12 year old. Although saying that once got me into a bit of bother.....
Personal favourites of mine are Highland Park followed by Macallan. Just noticed they've repackaged HP and ditched the Orkney sunset imagery for a more traditional appearance and shape. Just noticed on ebay that a special bottling of HP 12 that I possess was going for about £280, so I might keep the lid on that one.
Slainte!