WordPress powers nearly 31% of the web whereas Blogger is controlled by the Tech Giant Google. Both of them have their advantages and disadvantages and comparing them is not appropriate as one is nearly a drag and drop (only some part) based method and other requires some coding respectively. But for the sake of a beginner who wants to start a site, this may help you in choosing the better one. In this, the comparison is between wordpress.com with blogspot.com and both of them are with free accounts. The reason why I have told comparison is not appropriate is WordPress may not require coding to start with but you have to know for some advanced features whereas Blogger must require knowledge on HTML, CSS, JS or jQuery and some brain to use available resources.
wordpress.com vs blogspot.com free accounts
First I want to start with security as it is must and required in these days. Blogger and WordPress are known from years. Off both Blogger is older.

1. Security in WordPress and Blogger

As a free account user, you need not worry about security. It is taken care by the providers itself. But Blogger has a slight edge over WordPress as it is from the Tech Giant. I am not covering Blogger as well known providers are also getting hacked. Both of them are equal under this feature.

2. Appearance (Interface)

Both of them have a good interface, a user can easily understand or memorize. Nothing to complain about both the interfaces. But the opinions may vary on this feature. People who like drag and drop and not much coding shall like WordPress. People who want to play with coding shall like this interface happily.

3. Guidance (Support)

In this WordPress may win but Blogger also. There are more no of sites providing guidance or support to WordPress users in every aspect (maybe). From the service providers too there is well-planned documentation. There are forums too for guiding users. Blogger too provides good documentation for initiation. The interface of documentation has changed recently. Compared to other this has less no of forums. The no of sites guiding users is also less. But reminding you every issue you face can be solved if you have a good brain in searching. Maybe in this feature WordPress can have a slight edge.

4. Look of your site (Theme or Template)

In most cases, any kind of user likes WordPress themes. They have their own look and feel. In fact most users like WordPress themes. But here we are talking about the free account. So ultimately Blogspot aka Blogger wins. The look in Blogspot templates is not that very advances but if you use Bootstrap templates you can NO! will like it. Not all the templates are good. You need to consider some factors in choosing it. So as a free account user Blogspot templates are better to Wordpress themes.

5. No of available themes/templates

As a free account user in WordPress, you will be provided with less no of themes and the main thing is there is no change to use 3rd party themes under this type (free account). On the other hand, Blogger has very large no of the 3rd party provided templates. You can choose the better one and apply. There are no limitations over this feature in Blogspot. You are free to go. A better choice is to go for Bootstrap templates as they are fully responsive and attractive.

6. Mobile Friendly

No doubt WordPress has mobile friendly theme features. Whatever the theme you choose it will be user-friendly across all the devices. Blogger has very large no of templates but it is your decision to choose the correct one. Always we need to think of Mobile users as they are the main traffic these days. One option for mobile friendliness is using Bootstrap templates. They do scale with device width so the user will not face any issues. The other option is you can make slight modifications in the code like adding meta tags and changing post body code.

7. Looks in various parts

Blogger comment system is not that good and it sometimes takes away the attractiveness of a good template. Recommendations for this are using third party services at cost of Page Speed and No of requests. You can also integrate Facebook comment box in the template and some template designers are providing this. WordPress has no such issues, it has a good overall appearance in every part of the site.

8. Customizing layout

WordPress does not provide access to customizing layout under the free account. The downside is you have to use the given layout. This is the main problem with it. On other hands, Blogspot has no restrictions over this feature. You can change every part of your site.

9. Footer credits and Advertisements

In WordPress, you have no chance but to give footer credits to WordPress. Those credits may be in different styles. Along with that, you will see random advertisements while using it on your site. There are no such issues with Blogspot. You are free to go without footer credits even if you buy/download the free template. There will be no advertisements too. The most important feature Plugins cannot be used under the free account in WordPress.

10. Ease of use

Under this WordPress wins. A person who wants to play with coding will definitely like Blogspot. But the downside of WordPress is no customization. You can change only a few parts like Navbar, Menus, Styles and some others This lets it down. No such issues with Blogger, users can add any code from different coding platforms like Github, Codepen etc. W3Schools is the main asset for HTML and CSS lovers. It has very large no of examples and guiding tuts for changing your template.

11. Experience in different aspects

Starting with blogger helps you to know how a search engine works so that you can parallelly run with great one after gaining some experience in the web field. This point is very crucial. I promise if you correctly use Blogspot you will never go to other providers. The experience you get will be very much helpful in WordPress too if you start a paid account.With Blogger you will come to know many important points that you need to consider for running a site. Mark my words it will be very very helpful if you start with Blogger.

That's it those are few points to consider. Some others like storage, earnings etc. But those are to be considered after you gain some experience in Web field. The conclusion is if you want to start a site freely Blogspot is best as WordPress without its main features does not fit to your choices. Users who do no coding mainly go for WordPress but there are more features provided by Blogger under the same type of account. I know coding can be easy for some of them but also there are many no of supportive sites that help you in every aspect. The main reason not choosing WordPress is you will not be provided with Plugins, Customizations, and limitations over earnings. But it is the best platform to run (On most cases) if you have a Custom Domain.