Best Mate's latest Cheltenham triumph means he is the first horse since Arkle to win three Gold Cups in a row.
Arkle's achievements in the 1960s have been matched by Best Mate
BBC Sport examines whether racing's new hero matches up to Arkle, a horse so legendary he was known simply as "Himself".
Both have won three Gold Cups, with Arkle winning his first against one of the best chasers for many years, Mill House.
In addition, Arkle won several big handicaps, where, because of his record, he had to carry a lot more weight than the other competitors.
So much better was he than all of his rivals that two sets of weights were drawn up for his races - one set for if he ran, one for if he didn't.
Arkle: Won 27 of his 35 starts, including 22 in his 26 chases
Best Mate: Won 13 of his 19 starts
In contrast, Best Mate has a light racing programme - with three races a season his usual regime.
Now that he has reached the top level, he always runs in what are known as conditions races, where horses run on equal terms, usually carrying the same weight.
But he has never finished out of the top two.
Verdict: Racing is a different sport from 40 years ago with horses run less frequently.
Best Mate can only beat what is put in front of him but although the Gold Cup fields he has faced have been much larger than Arkle's, he has not had to face as strong a rival as Arkle did with Mill House.
Best Mate's connections would never ask him to shoulder the weights that Arkle carried.
That is perhaps to their credit but it means that Arkle will always win any achievement comparison stakes by a distance.
Best Mate is an excellent jumper. He has never fallen, and never seems to look in danger of parting company with his jockey.
Arkle, on the other hand, was not always the smoothest of jumpers. He had a bizarre quirk in that his forelegs crossed when he cleared an obstacle.
And although he too never fell, he made several blunders during his career, which occasionally cost him victory.
Verdict: Best Mate takes the honours.
Both horses were ugly ducklings but Best Mate has blossomed into a beautiful specimen of a racehorse.
He looks powerful but perfectly balanced, and his manner is alert and quick-witted.
He walks in a proud way as if he knows that all eyes are on him. "He thinks he's Arkle," his trainer Henrietta Knight once said about him.
Arkle, however, had a waddling walking style and a squat physique.
But he had a very gentle manner, with some describing him as having almost human understanding.
Verdict: When it comes to a beauty contest, Best Mate gets the sash.
Arkle was a national hero in Ireland and his fame stretched beyond racing circles with letters sent to him addressed simply "Arkle, Ireland."
Despite the fact that only those over 50 can really remember Arkle, he won a recent poll carried out by the Racing Post to find the all-time favourite racehorse. Best Mate wasn't in the top three.
But Best Mate attracted a crowd of 5,000 at an open day last September to mark his dual Gold Cup triumph.
And surely more will attend this year after his rapturously-received treble, and his fame will also spread further than the narrow confines of the racing world.
Verdict: Arkle is still well ahead but Best Mate is making up ground.
Arkle became - and remains - the benchmark for all chasers
Best Mate has not yet had the luxury of historical hindsight but he has become a modern hero and has answered the call at one of racing's neediest hours.
And he could go on to win four or five Gold Cups.
Verdict: Arkle had the advantage of a headstart but Best Mate is coming with a run.
"I don't compare Best Mate with Arkle," said trainer Henrietta Knight. "It's looking ahead that I prefer to do."
And comparisons are futile because Best Mate's career is still in full flow and it is impossible to compare two different eras.
But comparisons are also inevitable. While Best Mate could well add to his tally of Gold Cups, for the time being Arkle's crown as the greatest steeplechaser of all-time remains intact.