Most of these designs are pretty nice, however there are a couple of things that should not be emulated. Just some quick, well-meant observations:

IMO, the two designs that stand out as the best are Le Tote and Apptimize, both for their crisp, clear layouts and well-harmonized, non-cliched colors. In both cases, the background imagery helps to communicate the story of the product: The background on Apptimize connotes measurement, which is the general purpose of the app. (One little nit with the Apptimize page is the over-use of the slab-serif font in all caps as you get towards the bottom of the page, especially the "News" section.)

On Le Tote, the background connotes a sense of sophistication and glamour. The page copy, testimonials, and background all work together so that you understand that this is a fashion startup oriented toward a certain type of woman: chic, sophisticated, and aspirational. She'll know this site is for her when she gets there.

Now onto things that would be better if different:

On Estimode, the background slider is so fast moving and distracting that it makes it near impossible to read the above the fold page copy. It's gratuitous design: the background change, though a clever idea, provides very little new information, and only detracts from trying to understand the information that is already there. And there is no way to pause the thing; I had to keep clicking on one of the selector bubbles to keep the slider still long enough to grok the copy.

Similarly, the background video of Hum seems gratuitous, for what meaning do we get from just seeing a bunch of cheery folks using their smart phones? There's not really a story being told there. The rest of the Hum page is quite monotonous with its single column layout and repetitive typography. The text is really getting into TL;DR territory.

On StatusPage.io, the page is informative, but the continuously moving right to left moving text is difficult to read. The GG Bridge background image is, unfortunately, a missed opportunity to convey meaning. Contrast that with the main image on BloomThat which captures the sense of the founding locale but is also informative of the story of the product.

Hope this isn't too negative; I write it here in the sense of identifying things that could be improved. Best of luck to all these companies in their post demo day fundraising!

https://www.statuspage.io might be good looking but it isn't responsive (on my desktop machine running chrome) and starts cutting off content if the window is less than 1218px wide. Ridiculous.

These are all the same design.

What makes these designs work? Do they?

I am no design expert, but these sites look like they could of been "top theme downloads" on a WP Theme site.

What a fluffy post, why is this unordered list of 10 designs on the front page at all?