do you cook much on stove? do you have windows nearby? Tomato/tomartoe...

how2girl is right, ducted is better.

Ducted extracts better and with less maintenance. But it might be difficult or impossible to do, for example in a two storey house with the kitchen in the middle so that there is nowhere for the ducting to go.

suzineedsahouse is right, different people have different requirements and what is important for one person might not be important for another person.

I have seen a house where a window beside the cooktop was enough for the owner (I did wonder how that works on windy or rainy days). Some people are happy enough with a non-ducted rangehood. Some people insist on a ducted rangehood and are willing to rearrange their houseplan if necessary to ensure they have space to install one. I have heard of people who have chosen commercial rangehoods for their home. I know of people who have a second kitchen outside in their alfresco area which they prefer to use for some of their cooking and sometimes even those have a ducted rangehood. (Btw as far as I know a gas cooktop only affects your choice in regards to how high above the cooktop the rangehood must be.)

I'd do a Google search on the brand just to see if there are any reviews/what others have to say about the brand, model, operational efficiency and after sales service. Got to admit it's not a brand I've heard of. Next, check the specs for drawing power of the extractors. Do they have a working model in the showroom? If it doesn't lift a piece of paper & hold it firmly against the vents then it's probably underpowered. Next, check how noisy it is in relation to the amount of draw it has. Next, are the lights sufficient.
I have one (not that brand) that's very noisy (3 settings) but does bug... all in the way of extraction.
There is a 3rd option in terms of type - called a downdraft rangehood. These are installed into a benchtop (usually a freestanding island bench), behind the cooktop & they rise up out of the bench. The ducting for this type is under the floor. They range in price from approx. $1750 up to $4000 for the swanky European brands.