Wondering why they all have "MXPhotos.com repeated several times on most of the sample pages. My preference is one logo and then some sample shots rather than repeating the logos. Of the ones shown I stylistically prefer the font in #1 (which is the second one.)
I like #1. Clean and eye catching. While #34 is also a good clean eye catching design, I found the .com to be too small to read unless the logo is substantially enlarged. Viewing it as is, it makes the name look like MX PHOTOSI.
I think 19 and 43 have most impact, but I prefer colours of 34, which feel a bit more subtle and have a little more depth.
I took a look at your very nice-looking website too. I think the final choice should be influenced by what the main focus of the website will be: if its motor sports, then the orange/black look is probably good, otherwise I prefer the green for a wider appeal.
Number 34 is the clear winner in my mind. Looks great as a black and white watermark and looks very interesting. The only other one I could see on a photo without being overly intrusive is number 1. Agree that the .com is too small on 34, however.