Travel Bags/Suitcase recommendations

Hi,
I would like to know from the regular international travelers here, what would be the best options for check-in luggage.

Given that the max allowed limit per piece of baggage is 23 Kg. Would it make more sense to use Duffel bags or is a strolly suitcase preferable? I think Duffel bags should be lighter but are the are negatives with these? Or any reasons suitcases would be more preferable?

Also please let me know if there are recommended brands/models for these?

Thanks in advance.

No wheels means you are subject to the cart mafia. Some duffels have wheels..

I think the biggest problem with duffel bags is the breakable items get broken. Have you ever seen how luggage is loaded/unloaded by many airlines ?

As for recommendations - See what suits your pocket. Search flyertalk forums for discussion on check-in baggage.

Hmm.. yes that's true. I guess it would be good for a second piece of baggage with only clothes, toiletries etc.
Any suggestions on good lightweight check-in luggage?

Aren't the carts freely available for use by everyone at the airports? Or do we have to pay for them?

Not all airports offer free carts.

Most airlines allow 2 bags i guess, so I usually take a suitcase and a duffel. Even if there are no carts, you can place the duffel on the suitcase and drag around.

The wheels on every strolly suitcase I've ever bought (and admittedly, I don't buy top-of-the-line) has died on me, just when I've needed it most. So for this extended trip I've opted for an ultralight backpack. I bought it secondhand to avoid that "steal me first!" look, so it's not pretty, but at least I can swing the blasted thing on my back if there's no cart around, and I can walk rather than having to depend on public transportation/taxi to get me to my hotels. Also, I'm limiting myself to 20lbs total inbound, and I hope that I can get way below that weight.