What iPhone app should I get to hold and view PDFs and technical text documents?

What iPhone app should I get to hold and view PDFs and technical text documents and technical photos?

The reader will be very important to be able to zoom and function well.

I would like good folder structures, and an easy way to add, modify and maintain the contents both from the phone and hopefully through the computer.

Its possible that the content could be via the cloud.

Is there anything that fits this description out there that people recommend?

I used to have airsharing, but I did not even like that app TBH.

TIA

Thanks guys,I will certainly check them out.

Its so nice to be able to ask a specific question and people share the knowledge that they have learned.

Thank you very much!



Are these able to be managed from the iPhone as well as from the computer for nesting and organization of folder structures?