Last year I got a 690 in GMAT. I prepared primarily from 3 books and 1 online test series.
Books:
OG 13 (+ its supplementary practice tests)
Test Series:
All these resources helped me a lot, and am thankful to these that I was able to secure a decent score. But unfortunately, I wasn't able to convert any program I applied to last year.
This year, I'm thinking of giving the GMAT again. And no prep is complete without a test series. My question is -- in your opinion, what online test series (Manhattan alternatives) should I join that will help up my score? Also, any suggestions for additional study material will be more than welcomed

Thank you.