What do you want to do? Do you even want to be an engineer? Plan this out wisely according to what YOU want to do. Talk to experts in the field, or go to a university where you can see what each field has to offer.
I'm a mechanical engineer. Most engineers get paid roughly the same amount regardless of the field, it really depends on where you work and what your role is. There are chemical engineers that do not get paid as much as their counterparts, while most of them are paid as much as the rest, like I said, it has more to do with where you work, not what you are.
Comparing each of these fields, I will say that all engineering is pretty tough, but each interesting in their own ways. Biomedical engineering is a relatively new field; while there are jobs, it is still a klunky little field, so to speak, and there are more opportunities to work as a professor than there is in the industry. Although it depends on the school the field is not a chemical engineering exclusive field, either, it incorporates biology and chemistry with chemical, electric and mechanical engineering where necessary. However, as a new field you get to see this field grow up before your own eyes and experience something completely different; and better yet, the rewards are almost immediate.
Chemical engineering has many field of operation, but the biggest that come to mind are pharmaceutical, foods, and petroleum industries. I have many friends from this field, and it was tough, but they have good jobs, nothing I care to work for, personally, but they find their jobs interesting and challenging, using what they've learned as well as learning as they go. I think besides civil engineering, it's the least that varies from college to real world.
Civil engineering is seemingly over-saturated, but there are sub-fields that fill up quicker than others. In my school, contract/construction management and structural engineering were the two largest fields, but there is much more - materials and traffic engineering come to mind. It's really an interesting field - mainly because I don't understand it and find it fascinating. There is always a demand for civil engineers, so don't be fooled if you're told this is over-saturated, it just seems that way.
Mechanical and electrical engineering are anything but dull - electrical engineers have jobs almost everywhere, and they are in high demand. A few years back the US Patent and Trademarks Office was giving a high sign-on bonus as an incentive for recruiting electrical engineers, because they are in high demand, yet there aren't enough graduates. I don't know how long this trend will continue, I know right now that I wouldn't be unemployed if I were an electrical engineer. Electrical engineers work in various fields, although the most I know work for power generation industries (but there are many sub-fields that I can't remember right now).
Mechanical engineering is very diverse, there are many fields to specialize in, and I could go on forever, but I encourage you to look over www.asme.org, where you'll find a lot of information about mechanical engineers. It may seem hard to understand, but believe me, after a few years of engineering a lot of it makes sense. Mechanical engineers are employed in the aerospace, manufacturing, pharmaceutical, automotive... well, virtually every industry that has a moving part. There are areas of specialization, notably machine design, heat transfer, fluid mechanics, structural, materials, nanotechnology... to name a few.
In the end, the field of engineering you choose, if you choose engineering, will depend on what you want to work with and where. I hope this helps.
Answered By: Josuan - 6/16/2011