I'd need five figures to rate...
.. I'm getting close. TWS Black Widow has arrived at our other house, but I haven't picked her up yet... (all my valuable or large deliveries get sent to our house we don't reside in)
But, for top 2 of mine I go...
Iron Man MkXLIII diecast - it has it all for a sixth scale. Multiple helmets, realistic head sculpt, arm and weapon accessories, batteries, good base, damaged Ultron MkI... costs though. Including customs tax it cost me roughly twice my other figures, and was more in the vicinity of my SS PFF.
T-800 Terminator Battle Damaged Variant - The jump in quality from my first and only Sideshow figure, to this, my first Hot Toy figure, blew me away... The likeness, two heads, the quality of the clothing and weapons (and sheer number of weapons and hands)
And then sitting below these two, but still outstanding is my AoU Captain America, and TDW Thor... both great likenesses and excellent clothing, but more less features all round... even the stands are more simplistic... I expect my Black Widow to be on par or a fraction below these two, due to the ScarJo likeness.... I'll tentatively rank these in order: Captain America, Thor, Black Widow...