Mamba and FDL are both much faster and better dedicated combat ships. The Krait MK II has more firepower. The Krait Phantom has better range.
Mamba and FDL are both dedicated combat vessels. If you want to use them for anything either than combat, they're useless.
The Python is superior to the FDL and Mamba when it comes to MLF, armour, jump range, cargo capacity, and passenger capacity.
The Krait Phantom has significantly lower cargo capacity, and less combat ability, than the Python meaning it can only really compete as an explorer.
If you only feel that all ships should only fill a dedicated role, that's fine - but many people disagree. Many of us feel there there should also be multi-role ships (which the Python and Anaconda definitely are suited to), but that multi-role ships should not excel in any one area.
The Python excels in too many areas as a medium sized ship. It is has nearly as big a cargo capacity than the T7 (a dedicated hauler), a larger cargo capacity than the Imperial Clipper (a large dedicated trader), nearly equal combat capability than dedicated combat vessels like the Mamba and FDL, higher passenger capability than the Orca (a large dedicated passenger vessel), and nearly as high a jump range as the Krait Phantom.
If you want a medium sized multi-role vessel, nothing compares with the Python.
Make the T7, Orca, and Imperial Clipper medium sized vessels, and they would provide worthwhile alternatives to the Python.
Pretending the Python is the only viable medium ship is either an ignorant argument, or a dishonest one.
Pretending I said the Python is the
only viable medium ship is either an ignorant argument, or a dishonest one.