Say I have $1000 to donate. Can you give me your elevator pitch about why I should donate it (in totality or in part) to the SIAI instead of to the SENS Foundation?

Updating top level with expanded question:

I ask because that's my personal dilemma: SENS or SIAI, or maybe both, but in what proportions?

So far I've donated roughly 6x more to SENS than to SIAI because, while I think a friendly AGI is "bigger", it seems like SENS has a higher probability of paying off first, which would stop the massacre of aging and help ensure I'm still around when a friendly AGI is launched if it ends up taking a while (usual caveats; existential risks, etc).

It also seems to me like more dollars for SENS are almost assured to result in a faster rate of progress (more people working in labs, more compounds screened, more and better equipment, etc), while more dollars for the SIAI doesn't seem like it would have quite such a direct effect on the rate of progress (but since I know less about what the SIAI does than about what SENS does, I could be mistaken about the effect that additional money would have).

If you don't want to pitch SIAI over SENS, maybe you could discuss these points so that I, and others, are better able to make informed decisions about how to spend our philanthropic monies.