Both offer some corrosion resistance (but not elimination) compared to steel and Alu. Both want special joining techniques and skills. SS is actually not as strong as steel is, usually. But both can be used in smart enough ways so this is a minor issue. Ti can be as strong as steel. Ti has a lower density then SS. But since Ti (as well as Alu.) have less stiffness then steel they need to be either made of heavier tubing or larger diameters to have equally still a frame. Both SS and Ti are made in a range of diameters and wall thicknesses. Neither tends to be used as fork blades or steerers.

The real comparison is incomplete without more details known and proper execution. Poor tubing selection or bad joining will be far greater a problem then any inherent differences between these materials. Andy.