Re: help me choosing next bottle
Welcome to the forums, aitor!
I find the Yamazaki 18 quite unique. It's certainly not just about the Sherry cask influence with this one, as there's so much more going on... Oxidative notes that remind me of older brandies, resinous notes that remind me of venerable malts along the lines of vintage Auchentoshans or perhaps even Glen Gariochs, as well as an intensely fruit component. Yet the Yamazaki is truly its own 'beast'.
As concerns other Japanese whiskies that might compare, dramtastic would doubtless be able to point you in the right direction.
Just as a 'shot in the dark', you may want to consider an older (such as the 25-year old) Highland Park? At the very least, it will be a pretty good match for the Yamazaki in terms of complexity and richness.