This depends on what type of card(s) you hold on each end and if you're booking airfare vs hotel/other travel. With Amex if you hold a Business Platinum then you are reimbursed 35% of points used for economy bookings on your selected airline or any J/F booking with any airline. 35% rebate works out to be slightly better than the 1.5 cpp that Chase gives you when using CSR points for all travel bookings, but Amex has this 35% rebate exclusively for airfare while Chase you can use for hotel, car rental, and other travel bookings as well. So I've used Amex travel to book airfare many times to use this feature/benefit, while I will use CSR to book boutique hotels, especially overseas because Amex points will never give you a 1.5 cpp value for hotel (or car rental) bookings.

If you don't have Amex Biz Plat then the comparisons are obviously different and Chase will win with being more valuable when used for their travel portal. Even if you only have CSP that gives you 1.25 cpp value at Chase Travel it will still be better than the 1 cpp or less that Amex gives depending on booking type.