I like to have this general rule of if you have 800+ on your first back, get triple Dorans. If you have 1200+ on your first back, get Catalyst. If you have 1600+ on your first back, get Large Rod. I do close to the same thing on Annie, but with an option to go Sorc Boots first because she is harder to go OOM with.
If you have to back at 800 because you were bullied, 3 Dorans will turn the matchup around fast and you can usually kill them on 6. If you have to go back at 800 because you got first blood, then 3 Dorans will generally guarantee you massive kill or zone potential to snowball HARD.
If they are playing pretty passively with some poke on you and you have to go back at 1200, Catalyst into ROA is pretty core. You become an immovable bruiser in lane, moreso than if you go Revolver imo but I don't have much experience with Revolver.
If your lane is so ridiculously easy and/or boring that you can buy half of a deathcap on your first back, then do it. Deathcap may not be the most "optimal" first buy, but there still is no way to get more DPS/burst in one item since the DFG got removed.