As a person that spent many years in marketing/sales and also had responsibility for human resources, the anser to your question is that it really depends! Where do your interests lie in working in the business world. While HR can be more generalized and consistent in its roles over all industries/companies, marketing can take many divergent forms depending on the industry, company and size. HR deals with all the issues that pertains to the human condition within an organization: administration of benefit programs, safety within the workplace, security issues if dealing with government agencies, risk assessment (usually tied in with finance), recruiting/hiring/firing, employee assessment and training, workplace procedures, and many more.
Marketing can either be a strategic role: market research and analysis, planning, new product development, future programs, new promotional campaigns, pricing of products, development of existing and new markets, etc. or tactical: selling roles, types of customers, frequency of contact, incentitive programs, etc.
It all depends on what you like to do and would enjoy doing. I really like marketing because it opens up the whole company to you--what is the vision of the company, what can be done to add to the growth, should we be going in a new direction, can we partner with someone to make our growth accelerate faster, should we eliminate products/services, should we build the salesforce to meet new demand, how can we increase profitability or do we sell for less but sell more, etc.
HR is interesting because you are trying to bring in the best people possible to do the their jobs, but you also handle all the problem issues as well. If you are unsure of which direction to go, you might consider taking personality profile assessments to see where your temperament lies. Just remember, in today's world, you do not have to stay in the same career for 40 years, you can change jobs/careers to keep it interesting throughout your work career. Education is ongoing, especially since you can do so much more online in your free time as home (just don't become a doctor that way!).
Answered By: SpenJohn - 9/3/2008