I have a Bogen 3001 with their basic 3D head (don't remember the number) when weight is the critical factor. It's a good, basic tripod IF you don't extend it too high. But a 35mm camera (inherently light) on a light tripod can be troublesome at extreme focal lengths and/or very long exposures. Consider hanging some weight (even your camera bag) from the tripod.
I also have a Bogen 3035 for MF and LF if I don't have to carry it much.
But my favorite is my Tiltall. I find this the best compromise between weight and sturdiness. I wouldn't backpack with it, but it's not a bear to carry. I put foam around the legs when using in winter and have never removed it. Makes it easier when carrying over the shoulder.
Consider how you'll use the tripod. For example, if you can keep the camera low (I never raise the centerpost unless absolutely necessary) and avoid extending the legs, you can get by with a lighter tripod.
As to the shape of the legs, in an aluminum tripod the 3 shapes to consider (IMHO) are round, round, and round. In fact, I'm not aware of a quality metal tripod with other than round legs (though I certainly could be wrong).