Being the OP for Erewards is a scam post, this is my 2 cents:

So I've gotten a number of miles and HHonors points over the years, which I enjoy. If you are going to do it, make sure you commit yourself to doing it so that you'll earn enough $$ to trade for miles/points before they expire in 1 year.

It's pretty easy and simple and the miles for NW and HHonors post immediately. For AA, CO, DL in a few days. US was a bit longer but more like only a week or so IIRC.

I put most of my $$ into HHonors.