@Purush - I think your question is not well formulated

And now let me explain why: you see, Wordpress is great, gives you sooo many options and all - that's why people love it.
the real question is not if "Wordpress > Blogger ?", because it certainly is, the question is: Will you manage to build on WordPress a better (or equally good) site as the one you have right now on Blogger?
Also, where will you host it? Blogger afaik is hosted on their servers and it's quite slow. Get a nice host, get a nice theme, work on your on-page and do a good job, and your rankings will INCREASE for sure!
That's why people prefer Wordpress, because you have so many more options. But if you don't know what you are doing, having more options will put you in the risk of taking bad decisions, and thus going down in ranks.
Let me find you a good metaphor
Blogger is like buying a pre-built, ready to use Desktop PC
Wordpress is like building your own computer with components you buy separately
If you don't know what you are doing, the "Ready to use" is the better option for you.
If you know what you are doing or you are willing to risk the ranks of your website to learn from experience, then the "build your own" is a better choice.