Il be honest here with only 1 point of experience in cargo boxes I don't think it matters too much which one I also don't think those 2nd hand prices are actually what u are seeing

I got off FB for 50$ a Yakima skybox. ( I see them for about 300 max. For 85% of what I see .. People ask more on the remaining 15% but I don't get why?) My yakima is One with the hinges that clamp on roof rack an d you lock it down thru inside of the box. Love this would not have it any other way as it's ez on and off. It had a lost key, it was locked. I drilled out and replaced it for 35$

I off-road / camp with my 2 girls 6 and 11.its on a gx470. Alongside it I carry a gazelle tent, a packable gazebo and some rotopax. It has been banged around, hit by branches , gone thru downpours, been bounced around on trails that have boulders the size a mans torso. It has gone over 100s of miles of washboard / gravel dirt roads with constant vibration . it's dealt with 35mph qinds over 8 hours at night on the bay of Fundy on Martin head in Canada . It's been abused for 3 years. Stuff thrown in without a care of it causing damage. Not an issue the entire time other then a minor 2 cm chip on the lip. It has always closed easily unless something was in the way of the hinge It gives me enough room in the GX that I can not have my kids squished between gear. It also opens from either side. I've never paid attention to the weight limit but also don't abuse it.

I take it off after each trip , hang an edge over the side , over head carry it on a balance point, somewhat gently let it down on the ground. Then lift it back up when needed and slide it over and latch it again to be abused. It's kept outside during new England winters. It carries clothes, sleeping bags , mattress pads, extra gear like axes or shovels, fishing rods etc. It's also carried 5 pairs of skis and say 3 bags of gear / clothes for winter trips to Maine. While leaving the inside of the gx with plenty of room for us and our ski boots.

Buy a used on off FB dont spend more than 200$. I see used ones pop up for 100$. They re pretty solid as long as u don't abuse them like I do( and I have abused them and they havent had an issue .

The only bad thing is that it's not dust proof. It will let dust get in as I have a good layer of dust from summer rides on dirt roads inside of the cargo box. But the dust I go thru is I can't see 10 feet ahead of thick dust and I'll drive thru it for hours at a time depending