Princeton (Mercer County) and Princeton Junction (which is in West Windsor Township, Mercer County) both have higher property prices, and better school and larger school district than Allentown (Monmouth County), therefore the tax is very high.
But because of the school district, the property values hold up better (although everything is in decline now).
Plaisboro (Middlesex County) is right next to both Princeton and Princeton Junction. Plainsboro has slightly lower tax than West Windsor and they share the same school system. Part of Plainsboro is owned and developed by Princeton University.
Beware of the property address - for example, the Princeton zip code, 08540, covers a vast area including West Windsor, Plainsboro, Franklin, Montgomery...etc. Just because a house has Princeton address doesn't mean it's in Princeton.
From Princeton across to Allentown, the lowest property tax rate are probably in Monroe (Middlesex County), Cranbury (Middlesex County), Millstone (Monmouth County), South Brunswick (Middlesex), and Franklin (Somerset) townships. These are more suburb/rural area. Cranbury has its own K-8 but they send their kids to Princeton for high school, so their property price is high too (but not as high as Princeton). Many towns are building new schools therefore taxes are high. Of course it depends how big or new or nice your house will be. But it's common for a townhouse in West Windsor to have $6K-$9K tax, while similar townhouse in South Brunswick can have $4K-$6K tax.
Princeton is a walkable town, although not much of a night life, but lots of cultural activities. It has a not-so-good area too, like any university town. Surrounding areas are all suburbs. If you don't have kids I guess it really depends on where you work (commute - where and how). None of these I would call "cities." If you enjoy city, work and live in NYC - higher pay and more fun.
Prudential Fox Roach (realtor)
http://www.prufoxroach.com/ web site lists property tax info on the listing. So does Gloria Nilson (realtor) too
New Jersey Real Estate - Gloria Nilson GMAC Real Estate
APP Data Universe is a good place to look up info.
APP.com | Monmouth and Ocean counties DataUniverse | Asbury Park Press
If you still like to live in Princeton but want low tax, looks into the development called "Griggs Farm". It's not in downtown Princeton. It was developed by the township. Half of it are affordable housing, but even for the market rate townhouses, the tax is quite low.