Poch. Poch is good enough for the mighty Spurs. Always has been, and likely will always be.
Otherwise...
Nearly unattainable:
If he leaves,
Simeone is definitely good enough, but almost unattainable (he earns more than double what Poch does).
Conte is damn good, but prising him out of Italy again may be difficult.
Unlikely:
Mourinho is definitely good enough, with a massive trophy cabinet, but he comes with a style the fans won't like.
Benitez likewise.
Possible:
Nagelsmann is an interesting one, but he's on a fast-track to Bayern and may not want a detour to Spurs given that he's managing what is essentially an identical project in Leipzig.
Brendan Rodgers is also an interesting shout - he's really not a bad coach, and by far the best of the British bunch.
Promising punts:
Erik ten Hag at Ajax - bloke took them to the CL semi, after a promising spell revolutionizing FC Utrecht in the Eredivisie. Another interesting punt would be
Marcelo Gallardo, at River Plate - he's only 43, but he's already the most successful coach in their history, having only managed them for five years and won tons of honours in that time. He's turned them around from the situation they were in when he arrived, and was touted as the next Barca manager last year.
Would be risky:
Ancelotti - he's a good coach, but he might be outdated at this point.
Pellegrini likewise.
Don't touch with a fudging bargepole -
Eddie Howe,
Gareth Southgate, etcetera. Eddie Howe has spent a brick-ton of money at Bournemouth, only to consistently stall in lower mid-table, with a decent offense held back by a routinely terrible defense. He's a decent coach (the English Bobby Martinez, more or less), but the step straight up to Spurs is too much. I'd prefer he proves himself at Everton or somewhere similar first. As for Southgate, he seems roughly in his element internationally, but utterly failed at club level.
