I currently have a Beta C23C top box, technically I also have a ferrari supertank but the work took that...
My top box when it was empty
I had the supertank which was very, very good. I highly recomend them.
A co worker had the older friction slider c23 and the c24 bottom roll cab, despite the friction sliders its held up well, its a good 6 years old and heavily loaded and used everyday. Its still holding up well.
Britool I have seen some that are 20 + years old and still fine, but on the other hand a boy I know got a top box and it buckled within a month...