For Blogging, definately both are best. It depends on niche. For example, if you are in a niche where you are mainly monetizing with AdSense then it’s okay.
My concern is about usability.
For an Affiliate Marketer, who need to manage tons of links WordPress is better. Because it allows to clock affiliate link into the short form, manage at one place.
Further, it can be expanded as features of WordPress is NOT limited.
You can read more: searching on Google, blogspot vs wordpress.
If 33.5% of world’s website is using WordPress, definately there are lots of reasons behind it.
I understand and I felt good to hear that your blog based on Blogspot is ranking well. But the selection of a platform should be done as per niche, requirement… everyone have own choice.
May be I am little biased about WordPress