Stainless steel's corrosion resistance is its primary advantage over aluminum and carbon steel.  While aluminum offers decent corrosion resistance in many environments, it's susceptible to pitting and galvanic corrosion, especially when in contact with other metals.  Carbon steel rusts readily unless protected by coatings.  This inherent resistance makes stainless steel ideal for outdoor applications, food processing equipment, and medical devices.
However, stainless steel is generally more expensive than aluminum and carbon steel.  Its higher density also means it's heavier for a given volume.  Aluminum's lightweight nature makes it perfect for aerospace and automotive parts, while carbon steel's strength and relatively low cost are advantageous in construction and heavy machinery.
Workability varies:  Aluminum is highly malleable and easy to form, while stainless steel can be more challenging to weld and machine, requiring specialized techniques and equipment. Carbon steel falls somewhere in between, depending on the alloy.
Ultimately, the "best" material depends on the specific application.  Consider the priorities:  corrosion resistance, weight, cost, strength, and ease of fabrication.  For applications requiring corrosion resistance above all else, stainless steel usually wins.  Where weight or cost are primary concerns, aluminum or carbon steel may be preferable.
Let me know in the comments if you have a specific application in mind – I'd be happy to offer more tailored advice!\n