power of Singapore passport.
If we're talking about ordinary tourist says, and if there's a requirement to drive on the same side of the road as in Singapore, Japan ought to be on your short list. Singaporeans are routinely granted 90 day stay permission upon entry, and there are lots of nonstop flights. Jetstar now has a nonstop to Naha (Okinawa), and it's under 5 hours 30 minutes. Tokyo, Osaka, and Nagoya are only about one hour farther away, and with a variety of airlines.
Medical care is great, safety is superb, public transport is excellent, the food is awesome, you've got practically any choice of weather you like (from skiing to subtropical), springtime is incredible (cherry blossoms), and everything just works. Living costs are very reasonable especially once you figure out Japan is not only Tokyo.
Foreigners are allowed to buy homes in Japan, and (to my knowledge) on an equal financial basis as any resident of Japan, with the exception of bank financing of course. (You'd have to pay cash.) I'm not necessarily recommending that, but it's possible.
There is no retirement visa or other easy way to settle there, but if you have tax-related motivations then you wouldn't want to do that anyway.
Ireland is another drive-on-the-left country, and they do have a foreign residence program, at least if you have some above average financial means. Unfortunately there are no nonstops from Singapore at present.
And how about Sri Lanka? Singaporean passport holders are among the very few who don't even need to apply for electronic travel authorization (ETA). Singaporeans are granted 30 day entry but can extend up to 150 days, also a rare privilege. Sri Lanka is only about 3 1/2 hours away nonstop, and it's affordable. If you want to settle there, they've got their "My Dream Home" retirement visa program with quite modest requirements (some minimum remittances, and that's about it).