It's an individual thing.
I know photographers whose writing personality is amazing, so the more personal/witty writing in their blog gets them closer to fans/potential clients and helps them.
Others have elaborate shoots and post behind-the-scenes and set-up images, which are interesting and hence attract readers (other photographers, for the most part, as far as I can tell).
Some just post single shots every couple of days that are of such high quality you want to follow them for inspiration.
I think they key is understanding your own strengths (and weaknesses) and your target audience.