Where can i find the top rated auto insurance?

I am 19 this month, own a house, and am employed full-time. I also am a full-time student. I got a quote from Allstate a few months ago for 390 dollars / 6 months. I went in today and got a quote from them again and it was 605 dollars / 6 months. But I noticed 50/100 coverage instead of 30/60. What is the cheapest auto insurance I can get? I have had no accidents nor tickets. I am looking for a company that will have the lowest rates.