Initial website design concepts

your middle section is not inviting enough and I have no idea what you're trying to sell other than non-descript guardian software of some sort. get rid of the dumb dog and make your headline bigger and more catchy and watch what happens. Change the right graphic some something stopping something about unemployment claims so I get the concept. forget the screenshots. doesn't work for this kind of product. people don't click with screenshots and unemployed claims. show some people trying to take an employer to court with a big circle and a line through it and that might work better. thats at least one concept even if it sucks. It get the idea across better than screenshots

Since these are the points you're looking for, here they are:

Structure I assume you mean layout of the homepage and not the actual site structure? As what Steven has mentioned, you're talking on about what the software can do, but not how it would benefit, or even be important to a visitor. You're not selling them the "why" aspect of the product enough.

Color Color scheme is fair. Of the 3, my preference is the blue based one.

Brand Strength Besides the logo, don't see much strong branding elsewhere. What happens when a visitor goes to a subpage? Where would the logo be then? Use the headers to re-emphasize the brand as well (eg using the same or similar type as the logo).

Effectiveness of design Again, its not so much of design here, but rather content. Nothing wrong with the layout per se, but nothing really pushing a visitor to click / view / try / buy. I may be wrong though when the site goes live and you monitor the heat map or analytics.

Hey, liked the first concept, looks more modern and clean. The only thing that doesn`t fit is the pink color, maybe you should try using another color. You also should use more whitespace between headers and paragraphs and work on the footer, the text align of "What people say" box is strange.

I really like where you are going on the third design. I think the site needs to be super clean with a slight edge. I'm not sure about your color choices on the third design though. Think about using a darker or bolder color to replace the blue. Also, maybe use the texture that you used in the second one for the header and footer. I think it is subtle enough to work and could add a slight edge.

I like the first one most, though I would use green color on the call to action -buttons, the blue does not show too well and the red is a bit alarming. Maybe those three buttons should too be closer to each other?

One thing I am thinking is that are the "dl trial" and "watch demo" buttons presented too quickly, not many people will do those things only after seeing the logo...