My buddy and I are both Barca and Spurs fans, but we disagree about which club is more exciting at the moment. He's excited about Xavi's potential to be a transformative manager along the lines of Pep. I'm more excited about watching Conte try to drag Tottenham's loser mentality up the mountain to glory.
I think there's interesting comparisons to be made between the relative strength of the squads and the potential of the managers. I think Barca have a slight edge in the squad based on the potential of young players to be molded into pieces Xavi can use. Of the current squad, the only established talent that I believe will be starters on the next championship side are MATS and FDJ (maybe Depay). There are plenty of young players that will potentially be in that side, but they don't have more than a season of high level play to fit into that category--Araujo, Garcia, Dest, Mingueza, Pedri, Gavi, and Fati.
At Spurs, I think that list includes Romero, Reguilon, Kane, Son, and maybe Tanguy. But after that, it gets slim in a hurry. Skipp and Emerson might be able to hang, and there's other pieces like Dele that might have a renaissance, but I think the squad has limited upside. That's not to say Conte can't be successful with them--I think they'll finish between 4-6 this season, but that this squad doesn't have a lot of league-winning caliber players at the moment.
On the managerial side, Conte is currently among the elite 5-10 managers in the world for sides with ambitions to win titles (Pep, Klopp, Tuchel, Nagelsmann, Simeone). Zidane, Flick, and Poch are just outside that group, and there's a number of other guys who probably deserve a shot with an elite squad too--Rodgers, Gasperini, Ten Haag, etc.
But Xavi is an unknown. As a player he was probably the smartest player and best reader of the game I've ever seen. His spatial awareness is unparalleled and if you saw him play it's obvious why his potential as a manager is tantalizing. That being said, this is a guy getting his first major gig under a ton of pressure. And if he is going to be truly transformational with tactics/style, it probably won't happen overnight.