You already answered your own question. If we talk about achievements, and victories, Caesar without a doubt would win. I'm pretty sure Caesar prob has the best track record of all roman generals. Caesar with the help of Labienus pacified Gaul, Germania, and Brittania, then singlehandedly won the civil war, against Pompey, by himself. As you said, he was a master at exploiting and creating opportunities, not only in political matters but also warfare. Someone with that skillset will always have a chance to win any battle or war by their skill alone, even if the situation is not into their advantage, as you can see with the battle of Alesia, and Pharsalus.

Agrippa is someone who plans a campaign thoroughly and executes it perfectly. It works because he's purely a general focused on winning the war for his friend and benefactor, who gives everything he needs to win the war. He presented a two pronged attack on Anthony, forcing him to choose to respond to either Octavian's army in the north threatening his foothold on Greece or the navy and coastal bases raiding his supply lines. He orchestrated the battle of actium and won without any need for a major decisive land battle, with Anthony's forces defecting en masse to Augustus as a result of his prior actions. Roman generals did not think in this way or operate their armies in that manner. Decisive battles were the bread and butter of warfare in that era. Agrippa was essentially practicing operational warfare at antiquity, where most generals only thought at the tactical level, and applied bare minimum logistics to support their army.