There are a lot of DC movies that are considered to be failures. They are actually failing really bad. Some say that this is because the movies are often rushed and they are not executed properly. The content of DC is actually very good. There are some stories that you will never see in Marvel. Some may think that the DC movies are flops.
They are not actual flops because they have made billions of dollars. They are just considered flops when they are compared to the gross income of Marvel movies. It is best that the success of DC will not be compared to that of Marvel’s although this may be hard to do.
There are a few reasons why DCEU never quite seems to be able to catch up to MCU but all in all DCEU is a hugely successful company that is always releasing new content and while some is better than others, you definitely cannot count DCEU out of the game. Part of the reason that DCEU never seems to be able to stand up to MCU is because MCU simply has a better team and more people at higher skill level working on their movies than DCEU does.
A huge component to the film itself which helps a film be successful is obviously the quality. This means everything from the skill of the animators working with CGI to pull off the incredible effects that are so well known by these companies. If Marvel has more or more skilled animators, their films are just going to be enjoyed more by fans and critics. Another big reason is because of the somewhat cult-like following of the man of Marvel himself, Stan Lee. He always appears in some kind of small cameo appearance in the Marvel films and he has such an overwhlemingly large group of fan and supporters.