In my opinion, it depends on your abilities and interests. For me, electrical and computer science and engineering are very easy. They are easy because I enjoy them very very much; Note that it doesn't mean I understand the topics quickly and easily, conversely, I usually try so hard to progress, but this doesn't bother me. Since I hate chemistry, so chemical is the hardest one to ME. I really love mathematics and physics. That justifies my interest in ee/cs.
electrical engineering and computer engineering
Chemical engineering is a slightly declining career field. IT jobs and engineering that focuses on technology has overtaken this field.
Civil engineering is the field.
Environmental Engineering
For some people it will be the hardest field in medicine but for others it will be easy as. It all depends on what you are best at.
Petroleum Engineering
depends what kind of engineering
In my Opinion, it is nuclear engineeringDesign
Engineering is a field or subject to be studied, a doctorate is a qualification in a field of study.
Telecom engineering
bioengineering and chemical engineering
Civil Engineering.