I don't have a favourite but I liked Salam Namaste and Bachna ae Haseeno...and I'm open to like Pathaan, too.
Bang Bang and Ta Ra Rum Pum I found rather weak (not the performances though) and I haven't watched yet War and Anjaana Anjaani.
Your favourite film of Siddharth Anand among these;
Salaam Namaste (2005)
Tara Rum pum (2007)
Bachna ae Haseeno (2008)
Anjaana Anjaani (2010)
Bang Bang (2014)
War (2019)
Pathaan (2023)
He repeats every leading hero twice in his movies that too consequently? Will he make the next one in the "Spy Universe" with SRK too