I used First Aid, Step-up, clinical microbiology made rediculously simple, and Kaplan Q-bank. I thought Step-up was the best study guide because it has easy to read tables that are good for memorization. It is basically all the information in BRS pathology (except in table format). If you use both First aid and step-up and actually learn all the material in them, you will do well. I was scoring around 70% on kaplan and got a 238 on step 1.
If all you care about is passing step 1.... you can do so by studying and memorizing everything in first aid alone. But if you want to beat the mean, I would supplement.