I'd not so much worry about the total wattage vs max per port, because the more devices you connect the less likely all are being fully exploited. Example is I'd have a phone, a tablet, say a Powercore and say a BT headset. The phone if you attempt to use at the same time will drop to typically 0.5A due to thermal throttling, the tablet usually can draw 2A, the Powercore usually 2A and the BT headset often as little as 0.1A , and as each device gets near to fully charged will drop its demand.
If you put a meter on these and begin loading up demand, the voltage and the current tends to drop, that actually initially INCREASES the efficiency of the recharge because that tablet in the above is only needing 4.2V of the 5V so it is in effect throwing away 0.8V but with a typical Anker product it would drop to say 4.8V and then the device (e.g. tablet) is then throwing away 0.6V rather than throwing away 0.8V. So a degree of contention is not a bad thing.
I'd say don't worry about it, just know in extreme situations of you plug in all devices all wanting a lot of power they will collectively charge slower until one of them lowers their demand (say as they get to 85% charge) then the other devices below 85% begin to charge faster.
What I do is I carry a Powerport 4 and an Aukey 12W. Most of the time I don't need 40W, but in rare situations I need more then I use a both to get 52W, and if one of them was to fail I have the other as a spare.
I travel a lot too. What I need is not just density but redundancy, so I do not rely on one single product. The Aukey's weakness is its only 12W and when used gets very hot, but its small so good as 2nd spare backup or to add to the powerful Anker products for rarely needed extra power.