I have a ton of opinions about this. I don't see #2 and #3 working that well unless the target field is in a developed nation. Option #1 seems the most tried and true, has the most accountability, and is the only one I've seen work well personally. I believe the other options could work, but there are a lot of things that have to fall into place, especially when it comes to society/culture of both the sending nation and the target nation. If God is controlling things then anything can work, however I've seen people go route #2 or #3 when it appeared to be their own ideas and not something God had orchestrated.
(that's the short answer)
\_ My blog: Discipulus Scripturae