I have been using ABCpdf for generating PDF documents in Classic ASP and ASP.NET for many years, and have always found it to be the simplest way to generate and manipulate PDF documents.
Not only can you create empty documents and add text and images wherever and however you like, but the feature I find most useful is conversion from HTML to PDF.
As an example, on one website I need to generate nice looking brochures from content from a database which changes frequently. I have created a protected ASPX page which retrieves the content from the database and displays it in HTML. I also have created some attractive PDF templates -- a different one for page one and for subsequent pages. Using ABCpdf I load the appropriate PDF template then overlay the HTML page. The result is exactly what I needed. ABCpdf also overlays page numbers and allows me to save the resulting PDF to the file system or send it straight to the browser as a dynamic PDF.
With my HTML and CSS I can also control things like how different parts of the content will break across pages, and ABCpdf understands and obeys this. About the only thing I found it wouldn't do were custom web fonts that weren't available on the server.
Let's face it, creating a PDF by placing items on different parts of a page is time-consuming and requires lots of tweaking along the way. If you're a web developer you know HTML and CSS and can probably produce results quicker working that way and converting to PDF using ABCpdf.
Of course if you have to generate PDFs by placing items on the page, ABCpdf does have a very useful feature where it will add a grid to the page during your development which really helps with positioning and adjustments.
I looked at other PDF components and found none that could do all of this so well, and quickly, and as easy. I know there are free PDF tools out there and ABCpdf is a comparatively a little pricey (starts at US$329), but for all the extra effort you would have to put in to get the free tools generating something like what you need, you could get ABCpdf doing the job quicker and better.
The other good thing about ABCpdf is that despite several version updates over the years, even the latest version is still backwards compatible so my old Classic ASP code and works side-by-side with newer .NET code.
You can download a free trial or purchase ABCpdf.NET from webSupergoo's website