TL;DR Should I downgrade my AMEX Platinum and Chase MileagePlus Explorer cards? To what?<Enter> <Enter>

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<Enter> Both cards are hitting the 1 year anniversary this month and I need to figure out what to do with them. <Enter> <Enter>

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<Enter> The AMEX I definitely want to either downgrade or cancel because it has a 450/year fee (only did it to get the 100k signup bonus last year). Any thoughts on what I should do? I've moved all of the points to Air Canada miles (United partner) and have a large amount of lines of credit across all of my cards (total credit utilization is ~3%) so I don't think I need to keep it (or any AMEX for that matter) open.<Enter> <Enter>

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<Enter> For the Chase MileagePlus card, I'm slightly more tempted to keep it since I fly United a decent amount and it opens up a lot more award seating...it's worth noting my husband also has this card and most of our joint miles are on his account.<Enter> <Enter>

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<Enter> I'm in the process of trying to get my number new accounts down so I can (finally) get a CSP and a Freedom in one go- see this post for full details<Enter> <Enter>

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<Enter> Any advice would be appreciated!<Enter> <Enter>

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<Enter> Credit Score: 780<Enter> <Enter>

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<Enter> Current Cards: AMEX Plat, Chase MileagePlus Explorer, Capital One Venture Care, Citi Double Cash<Enter> <Enter>

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<Enter> Points/Miles: I fly pretty exclusively on United and don't stay in hotels; I go mostly between Amsterdam and the DC area