Best engines and transmissions, in your opinion

[RobbieL2415]

If your choices span multiple generations, be sure to specify which ones.  They do not need to be a combination, i.e. used together on a car.  Choices should be made based on ubiquity, reliability and performance.

Engines:
1: GM LS (All generations)
2: GM 3.8L V6 ("3800", Buick V6) (All generations)
3: Nissan KA I4 (Either KA24E or KA24DE designations)
4: Toyota S I4 (5SFE, used in most Camrys from 1990-2001)
5: Ford Small Block V8 ("Windsor") (All generations)

Transmissions:
1: GM family of four-speed electronically controlled automatics (4X-##-E)
2: Ford MTX-75 5-speed manual
3: Fiat MR6/F40 6-speed manual (used primarily by GM)
4: Toyota AM140E 4-speed automatic
5: Borg-Warner T-56 6-speed manual AND its successor, the Tremec TR-6060 (used by GM, Dodge, Ford)

[Takumi]

I am very, very biased to Japanese engines, but there are some domestics I like as well.

Engines:
-Toyota JZ I6 (1990-2002 Toyota Supra, 1989-2007 Toyota Cressida/Mark II/Chaser/Cresta/Verossa, 1991-2005 Lexus GS300/Toyota Aristo, 2000-2005 Lexus IS300/Toyota Altezza, numerous other Toyotas that weren’t sold in the US). Much more common in Japan than here, available in 2 displacements (2.5L and 3.0L) in naturally aspirated and turbocharged versions. Very popular engine for tuners to swap into cars because of its tremendous power potential.
-Honda K I4 (2001-present). Overall Honda’s best 4-cylinder. Too many variants to list, but my favorites are the K20C1 in the current Civic Type R and the limited-production Mugen-tuned K20A in the 2007 Civic Mugen RR.
-Honda J V6 (1997-present). Particularly the J37 that was used in several Acuras a decade ago. I have one and it’s phenomenal, though it has a couple of imperfections.
-Ford 5.0 Coyote V8 (2011-present Mustang, etc.)
-Ford 5.2 Voodoo V8 (current generation Mustang GT350)
-GM LS V8

Transmissions:
-Getrag Toyota V160 (1993-2002 Toyota Supra twin turbo 6MT)
-Aisin Toyota R154/Jeep AX15 5MT
-Toyota A650E 5AT
-Toyota A340E 4AT
-any 1990s Honda 5-speed manual
-T56 and T6060
-whatever the 6AT in my TL is

[kphoger]

-any 1990s Honda 5-speed manual

Oh gosh, yes!  A thousand times yes.

[wriddle082]

The Toyota 22R and later 22R-E (2.4L I-4) were unstoppable.  They were standard in every standard truck and Tacoma from the early 80's to whenever the last redesign was that increased it to a mid-sized truck (probably 2004 or 2005).

The Jeep 4.0L I-6 was also an excellent engine, with torque all day long.  The 5.3L V8 in my 2005 GMC Sierra doesn't even come close to having the torque of my old 1998 Jeep Cherokee.

[Max Rockatansky]

I had a 2012 Ford Fiesta with a 1.6L in-line four and a six speed dual clutch PowerShift transmission.  That was by far the most reliable long term engine I've had in a car and it was perfectly geared for good gas mileage.  I averaged 42.4 MPG over about 153,000 miles.  I'm aware people complained about the PowerShift being too firm for an automatic being shifts but it never bothered me nor gave me problems. 

Someone mention the GM LS series.  The L99 variant I had in my 2010 Camaro had be the most wonky of the LS series.  It made no sense to have cylinder deactivation on a 400hp car.  The L99 has some weird field injector warming issues that it made it sound like a person was inside your trunk knocking.  The engine was prone to getting stuck in a retarded spark meant for low octane fuels which required a weird fuse pull to reset. 

An older engine that I really enjoyed was the turbo Buick 3.8.  That was certainly not the best design but the sudden surge of power was a riot in the older G-Body cars.  I always wanted to try the turbo 4.3 Chevy V6 to see how it would compare. 

I do enjoy the 6.4/392 Apache Hemi in my Challenger.  I highly doubt that such a large displacement iron block V8 will be available in future muscle car.  I'd hardly call it a modern design but it is nice being able to spin my wheels in almost up to 40-45 MPH if I so choose. 

[LM117]

The Jeep 4.0L I-6 was also an excellent engine, with torque all day long.  The 5.3L V8 in my 2005 GMC Sierra doesn't even come close to having the torque of my old 1998 Jeep Cherokee.

It was a sad day when Chrysler killed the 4.0L after 2006. Those engines are bulletproof. I've got a 1999 Cherokee that I've had since April 2007. It had 80,000 miles when I first got it. It's got around 231,000 now and still going. Just about everything on the Cherokee has been a problem except for the engine and transmission.

I'm glad the 4.0L did not have the shitty 46RE transmission that the Dodge V8 trucks had in the 90's. I have yet to meet anybody that had a 90's Ram or Dakota that did not have transmission problems.