Water heater recommendation

Good day. Winter is coming and it's really annoying. I'm planning to buy a tankless water heater. I checked all of the water heater on Amazon and in this site http://www.elreviews.com/tankless-water-heater-reviews/. There so many choices in there and I'm confused. Please help me with my problem, give me some suggestion and advice on what would be the best water heater that I should buy. Thank you!

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