Quick answers:
Carry-on only.
Soft-sided.
Eagle Creek for both durability and warranty.
Another Eagle Creek fan here, but I usually take 4+ week trips, pack for a week, do laundry along the way and only check a bag when the plane is too small for the bag I'm using.
Eagle Creek does make some larger soft-sided roller bags, but the bigger the bag, the heavier it is before anything goes in it and the more likely it will be packed with things that aren't really necessary.
My largest bag is an expandable soft-sided 2-wheeled Eagle Creek Load Warrior. The last time I used it was on a 4+ week trip to Italy in 2017.
As you can see from these measurements and volume, the depth is what expands: 22x14x9-11 in. 41-45L. 5.5 lbs. The unexpanded interior is 14x7, all but the top which is 14x6. It's no longer made, but similar to this 4-wheeled, heavier, smaller capacity one.
I love this bag, but I've since switched to a smaller, expandable, international one. The last time I used it was on a 5+ week trip to Portugal and Spain in 2019.
It's the Eagle Creek International carry-on. 20.25 x 14 x 8-9.25 in., 36-39L, 4.5 lbs. Interior bottom 13x6, middle 14x6, top 14x5. It's also no longer made. The updated version is made slightly differently and is a bit heavier.
My bigger challenge is the personal item or tote, especially on European airlines. For example, if I fly Aer Lingus next year, their personal item limit is 13x10x8.
Due to shoulder issues, I'd hoped to use a backpack for my personal item, but the two I own are both a bit too big, as is the other one I was considering getting. So I have a little shopping to do, too. It seems like nothing is perfect.
Good luck with your shopping and decision-making.