Could the Benefactor Be a Shadowbroker?

Yap, Shadow Broker is my first guess for Benefactor, the second one being The Illusive Man (though there is an issue with anti-alien agenda which *seems* not to be the case for Initiative), and then possibly some Citadel Council members, some cooperating Specters, some cooperating military commanders (like Hackett and counterparts from other races), Aria, etc. Heck, it is even possible that Initiative was founded by Geths or Collectors.

Of all of them Shadow Broker makes the most sense, agenda seems to be similar, and arguable SB has the greatest interest in colonizing Andromeda (with communication like Quantum Entanglement it would strongly increase Shadow Brokers resources in something like... 600 years). It is a bit more complex if Liara was a Shadow Broker already by that time.

On the other hand, Illusive Man could have been interested both in making sure that some humans survive, and at the same time use Initiative to gain access to a number of secret projects being developed by other races. Initiative is using a lot of state-of-art designs, and equipment restricted to specific races or organizations (with "permission" to use them in Andromeda only), but by participating in the project TIM would have access to all the blueprints.

Geths are a nice idea: they were the originators of Andromeda scans, we do know that they had their own agenda, and they can be easily incorporated into SAMs. There would be probably some problem with getting all the funds and intelligence, but it is still a viable possibility.

Eventually, it is entirely possible that Benefactor is/are:

- someone(s) that traveled to Andromed on Nexus / on one of the Arks

- someone who appeared in the original trilogy for a few seconds, but was then one-shot by Shepard in one of the side quests.