Duffel bag or Carry-on small/medium size suitcase for a 4 day trip?

I'm going to Paris for 4 days next month and I'm taking my Peak Design everyday backpack 20L for when I'm out and about in the city as well as carrying my tech etc for use while I'm on trains but I'm torn between pairing it with a small or medium suitcase for my clothes and anything I might bring back or just taking a big duffel bag.

I read a few articles that discuss this and said to consider cobblestone roads when taking a suitcase but I've also got eczema and can't carry fabric handles for too long otherwise it hurts? I'm really not sure, any advice or recommendation would be highly appreciated. If it helps, I'll be staying at a hostel and I'll be taking 2 trains to get there and 2 to get back.

For reference the duffels I was looking at were the Shibuya Weekender by Horizn Studios and the Tumi Voyageur Just In Case Duffel Bag.

The suitcases I was looking at were just generic ones.