It will depend on what you want the recipient to do with your document:

MS-Word
This format readily makes your document editable, therefore it is best for this to be used when editing is necessary. It could be that you are sharing information with someone and would need their input; for this reason Word is preferable.

However, for resumes being placed on job boards or with an agent/recruiter this format in Word should be preferable as a tracking system is commonly used to 'fish out' relevant files. Always ask for what format is best to submit especially for resumes and if either is preferred it would be best to preserve your arrangement with PDF.

PDF
In the case no form of editing is necessary, the PDF format of your document should be preferable. When documents are sent in this form, you can be assured that all your modifications and settings (font, arrangement, style) can be preserved over different computers, locations and software.

With this reason, PDF should also be preferred for submission of class assignments, project works and the likes.

You also get to avoid battling with printer settings when your convert to PDF

P.S: Avoiding using trial versions that could leave signs/marks on your document.

http://allavosiyatalk..com.ng/2015/11/ms-word-or-pdf.html

What do you think?