Well you have started on a good base and at the top end really.
Where are you based????
is also well worth and to compare against the 18yo. Be interesting to see if you think the 18yo is the extra money after you taste the 12yo. Powers 12yo
is also another cracking blend and more interesting than the Jameson's to me.
There are still a few you can try with varying characteristics.
has always been a great value for money blend (70% Malt) and I prefer it over the Bushmills 10 & 16yo
If you want a decent Bushmills
Malt I'd go for a cask strength sherry cask
from Bushmills which are usually not much more than the 16yo. Usually only available in duty free and specialist shops though.
If you are in Europe try and get your hands on Redbreast 15yo
this is my top Irish for the last couple of years. However if you search ebay sometimes you can come across the now defunct Jameson 15yo Pure Pot Still
released for the Millennium. Another cracking bottle if you are willing to spend a few quid more.
Also on the higher price side is of course Midleton VR (Very Rare). This stuff is probably the smoothest easiest Irish you can drink. Just a bit too expensive and too smooth for my liking.
& Knappogue Castle
are also other Single Malts which are smooth but lighter than the Bushmills, potstills and potstill based blends.
Should keep you going for a while