On the homepage above the fold, avoid carousels altogether.
A quickly rotating image distracts attention away from the CTA button.
What I usually recommend is to either have a static background image or a slowly moving background video, especially if it is well-integrated with the text & CTA(s) above.
I wrote an article on my blog about the Pros and Cons of a Homepage Background Video.
By a ‘slowly moving background video’, I’m thinking of something like this, for example: https://whynotblue.com/
The moving water looks cool, attracts your attention for a second, then you actually focus on the headline above it.
Opt instead for user-initiated carousels, if any.
Keep the elements on top of the image fixed (headline, subheadline, CTA) and only change the background image.
My research on this
1. A case study by Grizzlyzoos showed that a homepage with a carousel received 2.06% clicks, while having a static image received 40.53% clicks. (source)
2. In the experiment on ND.edu‘s carousel, 84% were on stories in position 1 with the rest split fairly evenly between the other four (~4% each). So the other slides besides the first one are basically ignored.
4. Auto-rotating carousels annoy users and reduce visibility (source)
5. Auto-rotating carousels get ignored. (source)
13. A/B tests by ServerTastic showed that versions without sliders outperformed those with sliders by an average of 16.48% in terms of revenue per visitor. (source – the original study page isn’t available anymore)