There are thousands of free Joomla templates available to download. There are different styles so that you can match a template to your website. Rather than simply picking the design that you like the best, you should consider the type of website that you have and find one that will match that.
If you are focusing on a niche for you website then you should look into the different designs that are available for that niche. If you are creating a fitness blog then why not have a theme that involves sports. However, if you have a computer business that you want a website for, then you will need to look for themes that are linked to that.
You will also need to look into the navigation of the theme. You want to make sure that your website is as easy as possible when it comes to finding your way around it. Just because you like the menu being out of the way, you need to work out whether it is easy to find.