But should it even be a debate? Sure, the young upstart Courtois has been grabbing attention—and the headlines—with his performances while on loan from the Blues at Atletico Madrid, but do a few eye-catching performances really put him ahead of Cech at Stamford Bridge? No. Not yet at least.
For all the criticism Chelsea receive for the way the club is apparently run, their treatment of Courtois up to now has been astute.
In the 20-year-old Belgian, they have a goalkeeper with the potential to become one of the world's leading talents. It was shrewd business on Chelsea's part that they snapped him up in 2011 for just £5 million from Racing Genk—a transfer fee they could arguably more than treble now.
And while they have one of the world's finest stoppers in Cech as their current custodian, Courtois is busy gaining valuable experience in Spain with the club that nurtured the talents of David de Gea.
Indeed, it's interesting to consider that Courtois should arrive in Madrid when the Blues could have kept him a lot closer to home with a Premier League club or one lower down the divisions. But while he has impressed with some outstanding performances, he remains unproven.
To be considered a peer among the likes of a Gianluigi Buffon, Hugo Lloris or Cech, for that matter, he needs much more than 18 months on his resume.
Where Courtois still has it all to prove, Cech is very much the real deal. In 416 appearances for the Blues, he has kept an incredible 194 clean sheets—16 of which have come this season.
At just 30-years-old, he arguably has his best years as a goalkeeper still ahead of him. This week will see him make his 100th appearance for Czech Republic in a season where he has continued to excel.
Some may counter the argument of Cech's experience over Courtois' by drawing parallels with the former's arrival at Stamford Bridge in 2004, but that view is flawed.
The Czech stopper signed for a similarly low fee to Courtois from French outfit Rennes and was widely expected to warm the bench with Carlo Cudicini the established No. 1. Jose Mourinho didn't see it that way and immediately turned to the then 22-year-old.
It was a surprise, yet for all that Cudicini had given Chelsea, he wasn't the world-class stopper the club needed. In some respects, Cech wasn't either. However, the Blues were in a position to reward that potential as the club was growing, and their path since that time has mirrored that of their goalkeeper.
What Courtois brings to Chelsea is the same potential of Cech all those years before but in somewhat different circumstances. His potential isn't going to win championships right now. It will not win Chelsea the Champions League, either. For a club with their ambitions, that isn't good enough.
What's more, we have seen the criticism de Gea has come in for at Manchester United as the Spaniard has adjusted to life at Old Trafford. Chelsea fans shouldn't fool themselves to thinking that playing for the Blues comes with the same pressure, but it does bring with it a weight of expectation.
It's an expectation that Courtois has, so far, not been given the opportunity to show he can handle, so why take that risk when you have Cech?
Who should be Chelsea's No. 1 next season?
For the best part of a decade, Cech has been an exceptional talent, one of the world's leading goalkeepers. He has suffered major head traumas that would have ended most players' careers, but he has bounced back.
The Blues have shown that with their handling of Courtois thus far, they're rather more shrewd than they're perhaps given credit for. His time will come but not just yet.