Where can I get a list of recommended PDF viewer and form-filler components that I can buy and install in C#? I query on C# component PDF viewer on Google and get a lot of hits, but I'm not certain what programmers have tried and liked.

Background: See, my employer is wanting me to build one in C# as a kind of training exercise, but also to be a product for sales lead generation for another product they sell. The employer is perfectly okay buying something, as long as it's good. I've learned VB6 and PHP, and know a little C and C++, so I'm trying to learn where people get the best-rated addon components for it, and especially for this PDF viewer and form filler thing he wants.