I've heard it said that at any given time there is a Nordhavn circumnavigating. I believe the first to do so was a N46 over 35-years ago. Around 2000, Nordhavn sponsored a marketing gig that sent a N40 round the world at fast pace.
A personal favorite of mine is the Nordhavn 57. Fast boat - easily does 200 nm/days and burns around 6 gph so relatively economical. It's a comfortable boat for a couple plus guests. Under $1m USD. Here's one - looks a bit tired but you get the idea.
https://www.yachtworld.com/yacht/1999-nordhavn-57-8978624/.
Another interesting approach to long distance power is Dashew's transition to the FPB lineup. Not many out there, but they are fast and impressive. Here's an interesting YouTube showcasing the FPB in difficult conditions.
www.berthoninternational.com
There are a number of other circumnavigatable boats out there - Delta, Northern Marine, etc. Size matters. Achilles Heel of any power boat is downflooding in very heavy weather. EDIT - might also consider a Diesel Duck. Notfor everyone - a bit of a submarine, but an option.
Diesel Duck 46-2 - Capital City Yachts
I know it's obvious, but I'll say it anyway - The more accurately you are in specifying your use-case, the more satisfied you'll be with the overall experience. If you plan to cross oceans, really bumps you into a different league. If you plan to just do hardcore coastal passagemaking, may cross the Atlantic once or twice and will have the time to wait for favorable season, you may not want the big-ass Nordhavn.
One plus I'll mention on Nordhavn - like Amel, it's a well respected boat that is easier to sell when the time comes. Although expensive getting into one, resale is decent so overall cost of ownership isn't as bad as it might be.
Best success -
Peter
(BTW - if I were a sailor, would be an Amel - very thoughtfully put together. Honestly, there are no power equivilents - even the Nordhavns are over-complicated and not really the same philosophy as Amel).