And how about the worst of both?
Best–Mr. Fusion from “Back to the Future”. Flux capacitor as optional factory accessory.
Worst–anything 2-cycle due to pollution.
There are lots of very good one’s but I particularly like the Saab turbo 2.0 liter from the early to mid-80’s. Powerful, fuel efficient, strong torque, pretty much bulletproof. Not sure how or why GM screwed up such as basically good engine - but they did so by the '90’s they weren’t the same.
Drove the last generation bmw 3series with a 3L straight 6 once. That’s the smoothest reciprocating engine I’ve experienced. That and the lag free response of the variable lift made it my favorite. A detroit diesel 60 series was a 2nd.
For transmission, I would say the 6 speed manual of Miata. Nothing I’ve driven felt as direct as that setup.
The 2.3 4 cyl in my Dad’s 75 Pinto is a contender for the worst.
Ed B.
I’ll second Ed on the 2.3 liter Ford. The aftermarket can make a ton of Hp from these things but every part but the block needs to be replaced. As for the best, the venerable Gen 1 small block chevy. It soldiered on for nearly 50 years and is still the mainstay for many racers.
There have been lots of good engines and no such thing as the best engine. Certainly Chrysler’s slant six and 318, and GMs 3800 are among the best. Depending of course on what you want in an engine. Do you want dependability, longevity, trouble-free driving, or power, speed, etc?
GM small blocks were the best. Go to any street rod show and take a peek under the hood of just about any GM, Ford or Chrysler product. You will probably be staring at a small block Chevy engine. The worst for me was the Yugo engine. 3 engine replacements and less than 2K on the clock. Runner up is any Tecumseh engine from any year. The GM 400 Turbo-hydramatic was the best transmission. They were also used by Ferrari, Rolls Royce, Bentley and Jaguar.
I would agree that the Chrysler slant 6 and the Chevy small block were real work horses. As for transmissions, the GM Hydramatic and the Chrysler Powerflite, later Torqueflite were pretty bullet-proof.
I’ll second @missleman on the Turbo-Hydro 400. Bulletproof. I’ll toss a manual trans, the Borg-Warner Super T-10 4 speed. Designed in the 60’s and still made by Richmond Gear. “If your arm doesn’t hurt, you aren’t shifting hard enough!”
Of the newer engines… The Nissan V6’s are extremely reliable.
Honda 4 cylinders are also extremely reliable.
From the 60’s and 70’s Small block GM V8’s were very reliable. Along with Chryco’s Slant-6.
Best at what ?
You can argue for the following.
The best 4 cylinder truck motor ? The Toyota 2.7L. The best 4cylinder sedan motor, Honda 4cylinder. The best 3/4 ton diesel pick up motor ; Dodge Cummins diesels. Best sedan 6 cylinder; BMW 3 series. etc…
There is no flat out, best motor. It depends on the use and the vehicle.
How can you argue with the electric motor performance in the Teslar sedan ?
There are very few right or wrong answers. It’s like saying…who’s wife is best ?
And transmissions ? Which one is better matched to it’s motor and chassis ?
And, older motors are so far behind the performance of newer ones, you need to stipulate what era. For example, there are many four cylinder motors today, that far exceed the performance of the Chysler slant six…
225 CI with 145 hp…today’s fours with less displacement have more torque, hp and arguably last longer, and run smoother !
Wards Auto World periodically prints their list of the 10 Best Engines but do not go into much detail to explain their choices. To me, the best engine is one that is inexpensive and easy to keep for a long time and a lot of miles and that would not include an engine with the complication of a turbocharger.
The worst? My 1971 Toyota Corolla 1.6. Toyota was still ascending the learning curve. It was the only car with an engine that I had to overhaul.
I liked the 2TC Toyota engine that looked like half a 426 Hemi. It would start at any low temperature. It was a pushrod engine and it was one of the first I saw with a rubber rocker cover gasket that sat in its own channel. Really easy after the Chevy 350s I worked on. The 400 Chrysler wasn’t one of my favorites.
Best by which metric?
For reliability, several Toyota and Honda motors would be right up there. The D-series engines from Honda were very hard to kill, fuel efficient even when hotrodded around by the kids who often drove cars with them installed, and as long as you kept up with regular oil changes and timing belt changes every 90,000 miles, would easily outlast the car they were installed in.
For performance you’d probably have to look at something like top fuel racing. Those engines, at 750hp per cylinder, are absolutely insane, accelerating the car from 0 to 100 in less than a second. They burn so hot that the exhaust sets the surrounding air on fire by separating hydrogen from water vapor and then igniting it.
Or the P&W J58-P4 engines in the SR-71, which in car parlance reached the sweet spot of their power band at around Mach 3.2 
(Though they would lag behind the Space Shuttle’s main engines, which produced the equivalent of 37 million horsepower).
Wards Auto World . . .
LOL
I looked at that list of engines, by the way
There are some problematic, unreliable POS engines on that list
I read the criteria for being on the list
A BS list, as far as I’m concerned
That’s like saying a car is Motor Trend car of the year . . . meaningless
Yes! I drove a Borg Warner aluminum case Super T-10 for years. Absolutely indestructible!
That's like saying a car is Motor Trend car of the year . . . meaningless
WHAT??? You mean to say the 1972 Vega (Motor Trend car of the year) wasn’t a good RELIABLE car??? LOL
Ancient history. They had improved markedly by 1991 when they gave the honor to the Caprice Classic
1990 Lincoln Town Car . . . Motor Trend car of the year
What say you guys?
True . . . ?
BS . . . ?
"They had improved markedly by 1991 . . . "
I clearly remembering reading Motor Trend back then, and it seemed like a worthless magazine.
It seemed like they were falling head over heels with every single car they reviewed. It seemed like they never had any criticism. In fact, it seemed like they were getting bribed by the car manufacturers to praise their products.