For these reasons, the Black Mamba is considered by many experts the world’s deadliest snake together with the Coastal Taipan.
The black mamba and coastal taipan have nothing on the Inland Taipan (Small Scale Fierce snake). And I have never heard of the Mamba being up there with the Eastern Brown snakes either. (Just confirmed from several sources that Fierce snake and Eastern Brownies are number 1&2.) If you have contradictory evidence that the Mamba and taipan are actually more venomous than these 2, please link to the source, as I find that to be either really interesting or erroneous information.
For ease, this is from the wiki page
Inland taipan
Inland taipan (Oxyuranus microlepidotus)
The Inland taipan (Oxyuranus microlepidotus) is considered the most venomous snake in the world with a murine LD50 value of 0.025 mg/kg SC.[6][90] Ernst and Zug et al. 1996 list a value of 0.01 mg/kg SC, which makes it the most venomous snake in the world in their study too. They have an average venom yield of 44 mg.[90] Bites from this species have a mortality rate of 80% if left untreated, although it is very rare for this species to bite. This species is known to be a very shy, reclusive and a laid-back snake that will nearly always slither away from disturbance. It is not an aggressive species and rarely strikes.[90]
Eastern brown snake
Eastern brown snake (Pseudonaja textilis)
The Eastern brown snake (Pseudonaja textilis) has a venom LD50 value of 0.053 mg SC according to (Brown, 1973) and a value of 0.0365 mg SC according to (Ernst and Zug et al. 1996).[5] According to both studies, it is the second most venomous snake in the world. Average venom yield is 2–6 mg according to (Meier and White, 1995). According to (Minton, 1974) average venom yield (dry weight) is between 5–10 mg.[91] Maximum venom yield for this species is 155 mg.[8] This species is legendary for its bad temper, aggression, and for its speed. This species is responsible for more deaths every year in Australia than any other group of snakes.[92]
So, the Mamba might be more dangerous as it is more aggro, but our 2 are the more venomous. I know that where their ranges overlap, the Eastern Brown will predate upon Coastal taipans.