it mainly depends on how much gold will you invest for the weapon and on what armor and helm you are using.
for the cheap one;
if you are ready to spend around 2.5-3mil and using endless 66 i suggest use drag sword, you can buy 100gl worth 2.3m or so
for the little expensive one;
if you are ready to spend 7-8mil and is using endless 66 i suggest use glintstone aegis.

take note: they're really outdated so investing on such weapon wouldn't be nice specially if you have a little much money for the weapon.
so i suggest maybe get a legendary weapon with 100gl they're worth around 600k-800k nowadays and save for better weapons with higher rarity and level.

good luck farming!