Question.
So, we know title tags and alt attributes are good to have for keyword density etc ... but are they as good as body text? Is it still better for SEO to provide some actual body text that uses the words - and include image based keywords as well? Any thoughts ... ?
Answer.
Success in SEO is down to knowing the ranking factors that matter most to the search engines and then implementing in a way that the site is still usable for human audiences "€“ we need to avoid SEOO "€“ search engine over-optimization.
Of the factors you mention, their order of importance is <title> tag (keep them them focused on 2 or 3 keyphrases only); then body copy (particularly towards the top of the document), then image tag alt attributes (these are most important when it is an image that links elsewhere).
For the other on-page factors, I would also recommend including keyphrases in headings <h1> and <h2>. Finally remember that off-page factors, in particular the link anchor text and content of pages linking to the page you are optimizing, are most important of all.