I want to create a blog to help with my SEO. Any idea of which free service to use? Or should I try to do it on Smugmug? Any ideas, suggestions, or examples are appreciated.
Zach Rohe Photography
Creating a blog will only help if you post new entries on a fairly regular basis. I'm always surprised to see blogs that are intended to drive traffic to a photo site where the last entry in the blog was from years ago.
You can use whatever service you would like.
Keep in mind that Blogger and Wordpress are blogging sites. They make it easy to add new entries to your blog. SmugMug's focus is photography, not text. Yes, you can have a blog directly in your SmugMug site - but it will take more work to create each entry. If you choose to host your blog on SmugMug this tutorial might help: https://school.smugmug.com/SmugMug-Tips/How-to-Make-a-Photo-Blog.
My blog (linked in my signature below) is hosted on Blogger; @Hikin' Mike's blog uses Wordpress.