Hello Phillip
My initial thoughts are that you should consider multi-channel options of marketing with all methods working in harmony together to increase brand awareness, rather than trying to decide between one method over another.
Direct mail is still the most trusted form of marketing, and gives your recipients something physical to keep and read at a time when they are not being bombarded by online advertising campaigns. As with any marketing, it's important to include all possible response options and a sense of urgency with your offer.
I hope you find this simple guide useful
Direct marketing mistakes, and how to avoid them
I wish you every success with your marketing.
Sally