All bikes in the $150-$200 are basically the same and are only a half step above an x-mart bike.
Buy what you like. After you decide what type of riding you enjoy (a few hundred miles down the road), spend some cash on a good quality bike.
As far as sizing, stop by your LBS and find out for sure what size you need.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.