I would go for text links with right anchor texts, assuming that you are talking about linking to your own inner pages. If you are talking about linking to external pages, it may not matter much. And if you need to really put the link to one of your pages in image then consider putting the target keyword in the alt tag of the image that has the hyperlink.

Text Links would be better with proper keywords as your anchor text and title.

nod nod. Just make sure you get your alternative text for your images right.

Actually both are good,but My point of view Image Link is more advantageous than Text link.
An image link is a graphic image that typically links to another online document, such as a webpage, PDF file, video, Excel spreadsheet, etc. Like text links, image links can also point to another location on the same page.
Alt text is "alternative text" that is placed in the code for an image. It is displayed when the mouse cursor hovers over the image (fig. 1). The text is also visible if an image is unable to load (fig.2). Alt text is especially useful to people using screen readers.

I would say Text over images but using both can't be bad. But don't forget that search engine love text...

Unless you understand, people never click on the picture link. Personally, I find links photos are not user-experience simple and focused on any site.

i also suggest you to go with text link navigation because that more seo friendly than image and also another reason of that thing is image make website heavy that is not good for search engine

I prefer text links for main navigation for a few reasons.

1. The keywords in the text will help marginally over alt text.
2. The page will load faster.

i also prefer text link on relevant keywords

Text links is the most effective way rather than image links. Its basic but worth it of your work in optimizing the site.