1) I think I can save more lives by being an organ donor.

There were about 6 thousand people last year in Canada who needed an organ transplant [1] and around 247 thousand deaths [2]. Of those deaths, about 1/3rd were prevented by existing donors. We'd be preventing less than 2% of all deaths in Canada if everyone got the donations they needed.

Donation is only viable in cases of brain death (~49% odds) [1], and I couldn't find any statistics on how often a donor body is actually usable (but I'd assume vastly less than 100% of those cases, since you have to die of brain death in a hospital and still have cardiac activity) All in all, there's a deficit of donors, so it's probably still helpful (unless you're a man who has had sex with another man, in which case you might not even be legally eligible; it's banned in Canada).

I think you're probably saving less than 1 life on average by being a donor. You'd probably do better to convince some friends and co-workers to sign up with, since organ donation is "low hanging fruit" (free, socially acceptable), and sign yourself up for cryonics (you can claim you've gone with the more complex "donate body to medical science" if you need a social excuse for why you're not an organ donor yourself)

If you're not doing cryonics, there's no excuse for not being an organ donor, of course, so don't use this as an excuse to wiggle out of doing one or the other! :)

[1] http://www.transplant.ca/pubinfo_orgtiss.htm [2] http://www40.statcan.gc.ca/l01/cst01/demo07a-eng.htm