Elliptical or treadmill

Which is best for weight loss and legs strength/endurance?

They are about the same for weight loss and endurance. Treadmill is weight bearing so that's better for things like preventing osteoporosis. And probably leg strength too.

But depending on where you are starting from and how long you are using them, it's probably not a big enough difference to matter. You should do the one you like and will stick to and then switch it up when you get bored.