I'll do you better than some graph - pure fucking words. Believe me, this is so one sided you don't need a graph.

For this comparison, I'm going to look at an atron, small booster, small battery, and all skills at V.

Small booster needs 15 CPU, 5 PG. Small battery needs (and this is with skills), 45 CPU, 12 PG.

Small booster can give up to 400 GJ in a single burst. Small battery provides a 156.25 GJ max cap bonus.

Small booster running cold, taking into account reloads, provides 18.2 GJ/s with navy-400's. Small battery's increase in atron capacitor takes it from 8.3GJ/s peak to 11.5 GJ/s peak, net gain 3.2GJ/s. Bear in mind the booster's regen rate is always there, the battery rate is peak and thus applies exactly at 25% capacitor. more or less cap left, lower actual regen.

Small booster can instead be loaded with 3 navy-150 charges. That's an injection of 150 cap every 12 seconds (approx the battery's one time bonus) with a 22 second wait after the third injection, due to reload. Average cap regen of 9.8 GJ/s.

Small battery against neuting gives slightly better looking stats. Not only does it increase peak regen by 3.2GJ/s, it also resists 25% of neut pressure, meaning the 11.5 total is effectively 15.3 GJ/s to neut out, an effective increase of 7 GJ/s.

TL FUCKING DR

Cap booster is 3x easier to fit, gives more GJ straight up without even needing to reload, gives more cap-per-second even taking into account the effective impact of battery neut resistance, and is overall just tits and arse better.

Cap battery is your mate handing you an extra $10 before you enter a bar. Cap booster is your bartender giving you a free drink every 20 minutes for the next 10 hours. He'll cut you off after 30 beers/shots/whatever, but I'm pretty sure you're already fucked or finished well before then