To be fair:
I usually sign up just for the initial bonus points and then never do them again.

I also do e-rewards routinely (historically better success rate for me). Redeem the "dollars" for airlines miles (or hhonors points) typically.

Lastly, the "best" rate of return (IMO) is the Survey Points for "miles" for Amtrak. Yeah, the success rate isn't as good (again, typically) vs. e-Rewards, but Amtrak points are valued at like $0.023/point which makes them more valuable than hhonors, AA miles, etc.

I can routinely get about 300-500 points/month for those. Keeps my Amtrak miles from expiring and in a year I have enough for free tickets along the northeast corridor.