I personally think an online form would be more simplistic and a lighter load. You simply have to fill in data, submit it, and insert the data to a DB. you could then format the data however you wanted for reports or e-mails etc. Having the user download a form, fill it out, and re-upload it is a longer process, mainly for the user. They have to wait for the form to download (server bandwidth issue), fill it out, and re-upload it (user bandwidth issue). Then you still would have to either store the form some place, e-mail it, or parse it to extract data and then insert into a db. So direct form entry though an online form seems more practical for me. You have more control over the presentation and manipulation of the submitted information.
Just MHO.