Ah - didn’t realize “reasonably easy to purchase” extended to purchasing again (and again). No, one of the sad, but also exciting, things about these single casks is when they are gone, they are gone.
Johnny Walker Blue is a great choice
Personally, I am not a great fan of Springbank. 10, 15 or 18. Highland Park 18 is a superb choice. Another recent find for me from Highlands is Clynelish 14 year old. Tasted it in Edinburgh recently and then purchased a whole bottle back home.
I love The Macallan and Glenfarclas but they do have a lot of sherry influence. The Macallan under ‘Fine Oak’ does not appeal.
Irish Whiskey such as Redbreast has some Sherry influence but under check. Had one 15 year old recently and it was great. I tasted few good Irish Whiskeys in Galway and Dublin last year - Jack Ryan ’ Beggars bush’ 12 year old ( TN: powerful. good depth and texture. Ginger snap on the finish) and Yellow Spot ( TN :slightly sweet and honeyed. not big but real good length)
If you are Ok with blended malts then JW blue or Ballantine 21 year old can be a safe bet.