First, I go by the handle NOEMDFAN because during the late 1980s - the 2000s, EMD made junk, instead of world class locomotives. In the face of competition, EMD withered, and chose to rest on its reputation. 

As a consummate "Gearhead," I like all types of trains and locomotives.  It's not that I don't like EMDs and Prefer GEs.  If anything, I prefer steam, but was born just after the end of mainline steam in America.  (With that being said, I've been blessed to have seen and ridden behind many steam locomotives.). 

Once upon a time, GM/EMD built THE MOST RELIABLE LOCOMOTIVES.  When they launched their sales assault against the mature Super Power Steam Locomotive, RELIABILITY and AVAILABILITY were their key issues.   GM had engineers all over the US that made sure that EMD locomotives were reliable and available. Remember, it took 4 EMD FTs to equal the typical articulated steam locomotive in Horsepower. 

Not so much after the early 1980s, as EMDs locomotives were under designed and engineered.  Quality and Reliability suffered.  You will remember the EMD 50 and 60 series locomotives and their continual problems.  While GP-38-2s and SD-40-2s that were just a few years older soldiered on for 30, 40 and close to 50 years without being rebuilt, the trouble prone GP-50s, GP-59s, GP-60s and SD-50s, SD-60s and early SD-70s and SD-75Is died young, with electrical problems and their over taxed prime movers giving many problems.  (Witness the Southern Railway's old GP-38-2s and SD-40-2s just now finishing their careers on the Norfolk Southern, while the GP-50s, GP-59s , SD-50s and SD-60s died a few years earlier.) 

As General Motors was struggling with finances in the 1980s, due to a mature car market (by the 1960s, every family in America had access to a car, many had two!), poor sales due to the economy in the 1970s - the early 1980s and having to radically change the automobile (EPA Corporate Average Fuel Economy Standards, EPA Exhaust Emissions Standards, dramatic competition from Japanese and German Cars, Budding Competition from Korean Auto Makers, NHTSA Safety standards, and Increased Vehicle Costs that made cars more unaffordable with wage stagnation), it used EMD as a "Cash Cow" taking its profits without improving its products.  The lack of reliability in its new locomotives was taking its toll on its market.

In the late 1980s, GM/EMD having no money to allocate for product improvement also ceded the Locomotive Horsepower War to General Electric.  Even locomotive rebuilder Morrison-Knudsen out powered EMD, by using Caterpillar's 3616 Prime Mover .  Although these locomotives, using the Big Cat Diesel proved to be unreliable as the Thrust Bearings in the Big Cats weren't up to the longitudinal forces applied to them in train handling, EMD would have done well to offer the Big Cat 3612 and 3616 engines as optional extra cost prime movers, as they did with their over the road tractor trucks.  With EMD's assistance the Thrust Bearing Issues would have been ironed out quickly and GM would have still kept market share.  

The combination of producing unreliable locomotives along with the optics of having a locomotive that couldn't keep up with the competition doomed EMD to be the second choice in the Locomotive Market.  This caused the sale of the Electro-Motive Division to Berkshire-Hathaway (changing its name to Electro-Motive Diesel).  Eventually and Ironically, it was sold off to Progress Rail/ Caterpillar. 

The King is dead:  Rest In Peace EMD.