Top 5? In what terms??!! Maybe that should be defined in another poll...
Ok...in not particulkar order here are my favorites as an engine builder looing for performance and longecity:
289 Ford - Bullet-proof small block
283 Chev - Another Bullet-proof small block
429 SCJ Ford - Brute power easy to get HUGE power hard to find motor
440 Mopar - Brute power easy to get HUGE power a little easier to find
5.0 (302) Ford - HUGE bolt-on market for great power and decent economy.
I think this should be broken down into categories, ie speed/hp diesel, old or modern.
anyhoo, here are my faves for modern passenger cars (last 25 years of cars) in no particular order.
2.5L gm tech4 -- not a big horsepower engine but was very reliable and would last forever if maintained properly. plus the one that was in my 86 Olds cierra was the only engine that would start in weather colder than -20 F.
3800 series 1 GM another bullet proof engine. I have had two cars with these, and they are great. will last forever and has a decent amount of pep and gets great gasmileage.
5.0L GM good engine, not much HP stock, but can be very easily modded to be a very powerful engine, and has a bonus of any SBC engine component will fit on it
5.0L Ford. another easily modded engine for more HP, and a solid reliability.
3.3L Dodge very reliable, good gas mileage, and one of our members has gotten almost 500,000 miles on hers. Wonder what the story is on her Trep...
For Older engines..
350 ci Chevy... easily modded for horsepower, and any component of a SBC engine is interchangeble
300 I6 from Ford. powerful and reliable for the size.
454 ci chevy Insane amount of HP available. Just hope you have money for gas....
Slant 6 from Dodge Probably the most indestructable engine ever made. I think they quit making these things becuase they never wore out, thus people would not get a new car.
I'm no leadfoot or speed freak, but the five motors I prefer are:
Ford 3.0 Vulcan V6
Chrysler 2.5 TBI 4cylinder
GM 3.1 V6 (1990-1993)
I've owned at least one of each of those motor, and know them inside and out. Some may not be fast, but they are smooth and reliable.
The five engines I hate the most:
2.5 GM Iron Duke. I hate this motor with a passion
3.8 Ford Essex V6. Head gasket blowing rod knocking POS
Chrysler (mitsubishi built) 3.0 V6. Water pump eating oil burning hunk of junk
GM 3100 V6 (1994-present) Intake gasket and head gasket blowing heap of crap
Any import engine.