The interesting thing about this question is that we might have a totally different list that the Romans would because we'd probably be looking at completely different criteria. One of the ideologies of the Republic was that office-holders were replaceable, and in a way they weren't really supposed to stand out. A lot of the major players we know about were important because they were polarizing.

The Romans really liked stern, conservative, morally rigid consuls; and they liked winners. Probably the biggest source for this moralizing of consuls is the early books of Livy. An alternate view is in Book 6 of the Aeneid, where Aeneas receives a vision of Rome's future in the underworld.

Some highlights:

Cincinnatus (5c.): After he had been consul twice, he retired to his farm. When Rome lost its consuls in battle they appointed him dictator and he saved the city from the Sabines. After this he retired again to his farm. His lack of ambition made him a good foil to the dynasts of the Late Republic. He is the namesake of Cincinnati.

Manlius Torquatus (4c.): Ordered his army to maintain discipline under pain of death. When his son disobeyed, he had him killed to the horror of his officers and co-consul. The phrase "Manlian Discipline" is still used to this day.

Decius Mus (4c.): When the Roman army was folding to the Latins in the first Samnite War, he charged into the enemy line alone (perhaps after consecrating himself as a sacrifice to the gods), frightening the Latins and encouraging the Romans.

Scipio Africanus (3c.) He's less legendary than the previous figures but his write-up in Polybius is nothing short of heroic. He turned the Second Punic War around and was the only man to defeat Hannibal in battle.

Fabius Maximus (3c.): Scipio gets all the credit nowadays because he was young and adventurous and makes a better movie hero, but Fabius kept Rome alive in Italy by refusing to give battle to Hannibal. In a culture as war-obsessed as Rome, it takes some resolve to "delay." He was referenced in an episode of 30 Rock.

Titus Flaminus (2c.): He was everything a Roman conqueror should be (at least according to the Greeks). He defeated Phillip V in the Second Macedonian War, but instead of despoiling Greece like the other commanders after him (Aemilius Paullus and Lucullus are the main offenders), he declared that "all of Greece will be free" and withdrew leaving the Greeks to govern themselves. Of course, the Greeks attacked Roman armies a few more times and by 146, Corinth was ashes and Greece was totally subjugated.

Maybe I'll give you more later. I'd like to see if people agree or disagree with me. I based this on the people the Romans (or their neighbors) seemed to admire, not the consuls I would necessarily choose.