My 2 cents:
If you're targeting top 10, I would recommend that you apply next year.
Bascially, unless you fit one or more of the following, then you shoud apply next year:
1) Your family is mega rich. (Last name Bush, Romney, top 10 richest family in India, etc)
2) You are from a very rare demographic/background. (ie, half native-american, half sudanese, etc)
3) You have insane leadership and/or work experiences (olympic medalist, started own non-profit charity that saved hundreds of starving kids in africa, lead a nation-wide strike, multi-million dollar successful start-up, etc)
If you fall into the one or more of the above categories, AND you have strong stats (at LEAST high end of the 80th-%ile or higher) , then yes apply in R3/4.
If not, then apply next year in R1. Why? here are the reasons:
1) You will have a much stronger application. No matter how prepared you think you are right now, trust me, you will produce much stronger app with a few months more of preparation. If you have weaknesses, you can adress them in these few months. If you haven't visited the schools, you have plenty of time to visit. etc etc.
2) R1 gives you a MUCH HIGHER chance, even with the exact same app. This is a fact. Schools have a lot more spots and are more willing to take chances in R1.
3) If you apply this year and get rejected, you will apply next year as a reapplicant which is not a good position to be in. Your app will be more scrutinized.
If you put the 3 together, you will have a MUCH higher chance in R1 next year. You have to ask yourself if you want the best chance of getting into your dream school, or a just a tiny chance. You have to ask youself, if you get dinged everywhere, what would you do. OR if you only got into a lower ranked school in R3, what if you had applied in R1, maybe you'd get into your dream school. You would kick yourself for a long time because you never gave it your best shot.
Usually people have no good reason to apply earlier, other than the "i'm anxious to get to school earlier" reason. I would say unless age is an issue, like you're pushing 33, 34 or something, then definitely apply R1 next year. The question you should ask yourself is, why not apply next year?