Weight Loss: elliptical vs couch-5k running?

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When I do the elliptical I feel like my *kitten* is being handed to me and I'm drenched in sweat. But my heart rate is usually between 120 - 135 even doing intervals.

When I do the couch to 5k (run/walk off and on) my heart rate will go up to 170, but I don't feel like wiped at the end.

Which is better for weight loss? Whatever gets my heart rate up more? The elliptical seems deceving because of how much I sweat and it feels like I'm constantly working rather than when I'm walking coming off a jog, even though my heart rate is the same.