Difficulty: Rollersetting was waaay more difficult for me to learn. There were times when I just gave up and put my hair in a wet bun. Flexirods were pretty simple.
Winner: Flexirods
Time it takes to do: Rollersets are more difficult for me, so they take more time.
Winner: Flexirods
Time it takes to dry: Flexirods take forever to dry because there are so many little rubber rods clumped together on your head, so there's hardly any room for air flow.
Winner: Rollersets
Curl definition: It's not even a competition.
Winner: Flexirods
Curl Lifetime: Another no-brainer
Winner: Flexirods
Products necessary: I use the same for each one: Leave-in and serum
Winner: Tie
Overall winner: Flexirods.
ETA:
Some old pitchas of my relaxed days.
Coupla days old flexirod set:
Fresh rollerset:
As you can see, the flexis rule when it comes to curl definition and longevity.