Can i get some advice on carryon luggage?

Both backpacks and suitcases are acceptable as carryons, as long as they fit into the carryon measuring box at check-in (you can find dimensions online). Since you are taking only one piece, I would go with a big backpack, especially if you are planning to move from place to place during your trip, take buses, trains etc. If, however, you are gonna be staying just in one place (e.g. one hotel), a rolling suitcase may be better, since it is more comfortable to drag in airports while waiting for connections.

I wouldn't choose hard-sided luggage because it isn't pliable when space is an issue. However, a soft-sided carry-on would be my personal preference.

There is a standard dimension for carryon luggage applicable for most major airlines. It is not very large, mind you, for your 2 weeks away. However, I would recommend that you get one which can be expanded in the event you made purchases while out-country and in that case just check it in as a check-in luggage. Hard or soft. The hard case dimension is rigid and not likely to allow you to squeeze contents like a soft case will. So, weigh your options. Might as well go with a check-in luggage instead not worry about having a carryon while waiting for flight departure. Samsonite and Delsey has good range of luggage types to suit any occasion. Reliable too. Have a scout around.