Clan McGregor is drinkable, although very, very light. Good party Scotch and summer backyard scotch. But is also light on the pocketbook - probably the cheapest blend you can find that isn't gutter water.
Famous Grouse may be the best value blended Scotch. It is the most popular Scotch sold in Scotland and I would daresay the Scots would know their whiskey best.
When you're ready to splurge, Wine and Spirits rated the top two blended Scotches 95. One of two was priced at $2500 per bottle. The second was Buchanon 18 Year Old, which goes for about $75 per bottle. I wouldn't pay $2500 for a bottle of booze even if I had that kine of money to throw away. But the Buchanon is relatively affordable and is top, top shelf. I can't think of a blend I like better.
Do check with your local B&M and ask them what they have in the way of vat Scotches aka single malt blends. BTW, Johnny Walker Blues is, I believe, a vat Scotch and is better than most single malts - as it should be, for $200 bucks a bottle.