Benchmark
JTS Brown
Very Old Barton
Henry McKenna
Evan Williams Black
Off the top of my head and in increasing cost order. All under around 12$ - 750ml, and all quite drinkable even straight.
There are also a few Bourbons which are decent mixers at an even lower cost. It's easy to find a decent Bourbon in the $25 range.
Now... Canadians? Canada has some weird whiskey rules. Bourbon, Scotch, Rye, all have some rules of the road in America. Canada's rules are loose and allow them to tinker quite a bit to produce a good, cheap, whiskey. For instance, the 9.09% rule allows other spirits, even wine, to be blended in and still call it Canadian Whiskey.
A very common strategy with Canadians is to distill some of the spirit to a higher proof (180-190) and age it at that proof. Some spirit is distilled to a more "whiskey" proof (140 or so) and aged at that proof. The higher the proof it is distilled to, the less congeners. Congeners willy nilly equal a hangover, but congeners also equal flavor. A very good whiskey will, through the picking of the distillation window, minimize the former and maximize the latter.
Anyway, then the two different proof spirits will be blended. This makes a much better product than an American blended whiskey which is whiskey blended with grain neutral spirits (un-aged 190 grain alcohol). The resultant Canadian whiskey is "thin" and lacking in a great amount of character, but it is smooth and avoids the mineral spirits taste of a cheap blended american whiskey.
So, if you like it, Canadian is a hella good whiskey for the money. I'm not sure why anyone would use anything else in a generic "whiskey and soft drink".
However, I like Bourbon, and there are decent Bourbons for the same price as a middle shelf Canadian.