That one is really tough… You will most likely get such a wide range of answers because there are so many different kinds of scotch. There are many I have seen here that are favorites that I wouldn't touch if it was free.
I would be careful about trying an expensive Islay. If you have never had one the experience can be…. Shocking.
I can throw out a couple bottles for you.
Glenlivet 21 - I have always enjoyed this one
Macallan 18 - It is good, but I am not sure it justifies the jump in price from the 12.
Highland Park 18 or 21 - HP used to be one of my favorite scotches. However, the flavor of the bottles I have had has changed dramatically over the last couple of years.. At least in my experience. My dad has noticed the same thing, and he lives in Missouri. I need to try a bottle to see what it is like now. I can usually only get the 18 around here though, and I can't get anything shipped to OK.
I would still recommend the 18 or 21 but with caution. It might be a little smokey for you.
Balvenie Portwood 21 - I haven't tried this one yet, but I have heard it is really nice.