Generally, this solely depends on your personal preference. Domain extensions come in many variations and it is up to you how you wish to present your site.
Country specific domains such as .UK or .DE domains are ideal for those who wish to advertise their connection to said country. The type of domain extensions you see used rarely such as .PHOTOGRAPHY or .DIAMONDS can make your site stand out compared to the more common domain extensions. There are many different reasons to go for one domain or another and it is entirely up to your needs which one you'll pick in the end.
In terms of SEO it is hard to predict how different extensions would affect your ranking, largely due to the fact that Google have kept a big part of their ranking system secret. However, it is clear that the domain extension has a much smaller impact compared to content, links, etc.
If you find yourself wanting more than one domain, it is possible to set up domain aliases or redirects, so they all lead to the same site. That way it will get even bigger exposure and it will make it easier for people to find it.