Brook, Jos Buttler's successor as England's skipper in the limited-overs game, has been charged with leading the once formidable white-ball outfit back to former glories, starting with next year's T20 World Cup in India and Sri Lanka.
But asked whether he'd prefer that global success or an Ashes triumph in the Australian summer leading up to the Asian tournament, Brook could only smile after admitting, following just a moment's hesitation: "I think it is the Ashes.
"I know I've taken over the white-ball captaincy, but the Ashes is the pinnacle of cricket for me, still."
The 26-year-old, who's been described by England's top run-scorer Joe Root as the best batter in the world, caused a stir when he gave up a Stg 590,000 ($A1.3 million) pay-day in this year's Indian Premier League with Delhi Capitals to instead recharge his batteries for his international duties.
It prompted a backlash from the IPL with Brook set for a two-year ban after he'd also pulled out of playing the previous year.
But he promised that no amount of money could have tempted him away from his England commitments because he wants to be in top shape for both the huge Test series against India over the next few months and be ready for the Australia trip.
"Definitely not at the minute, I just want to play cricket for England," said Brook, when asked if he'd accept any lucrative franchise offers.
"There's a lot of cricket and I'm looking forward to all of it. I'd like to play every game but if I require a week off and that's the best thing for my game then I'm sure I'll be allowed a week off."
Brook may not be eligible again for the IPL until 2027 under the league's new rules, so he could, in theory, be spurning well over Stg 1 million ($A2.1 million) by missing two money-spinning years.
"That's the rules, so if I do get banned, fair play," he shrugged.
"I'm completely committed to playing cricket for England. If that means franchise takes a step back for a little while, so be it."
Brook can't wait to have another crack at Australia after having stood in for Buttler as captain in the ODI series last year that Mitch Marsh's team won 3-2.
He shone in that series, averaging 78 with a strike-rate of 127.86, but the defeat still rankles.
"This might sound a little bit stupid but when you're captain, it almost makes you want to win a little bit more," he said.
"It's not me saying that when I'm not captain, I don't want to win.
"But I'm a very competitive person, I hate losing at anything. Hopefully I can bring that competitiveness and have it in a good way around the group.
"I'm going to be myself, as much as I possibly can be. If you play cricket for England, we're living that dream. As a 10-year-old looking at yourself now, you'd be absolutely buzzing and over the moon."
