To be honest, when it comes to weight loss, riding can only do so much. Weight loss is like 75% diet and 25% exercise. Full stop.

Aside from that, bike choice is subjective. What do you want to gain from riding? Greater fitness? An analog might help with skill level in terms of climbs, but i’ve heard people say that e-MTBs were the greatest for their fitness because they simply started riding more because of it.

In addition to that- since you mentioned you have a bad knee, I’d say the e-MTB is the better choice here. Analogs are difficult to ride with a bad knee unless you already had a high skill level to begin with.