So many wonderful cars out there. The old stuff is great for high days and holidays but is still old and the poor ventilation, lack of adjustment in driving positions and harsh suspension woulld ause me to fall out of love quite quickly. (Except an E type, I would cripple myself and still love an E type.)
Something reasonably modern but not too extreme. Also different enough from the MX5 to make it a genuine choice depending on my mood.
First choice would be one of the newer generation Astons. A Vanquish if money was no object, but a nice DB9 or Vantage would do just fine. I have driven both quite extensively as a track day instructor and whilst I love the V8 Vantage, there is something special about the V12 in a DB9, it is a sublime mix of relaxed cruiser and screaming monster when you get past 4500 rpm.
It would be followed very closely by an F type R. (Or even an SVR). They are quite mental if pushed hard and make you sweat.