It depends on the criteria that are important to you.
Ball used to be an innovative American manufacture.
Nowadays its a name in a corporate holding and not American at all
Sin is German and still proudly so an their materials technology in their cases is interesting innovative and practical.
I agree that they are okay in Build quality, but side by side I don't agree that they are better than Sinn
I've not scratched or slowed either Sinn and one of those is black!
If extremes are your thing then the UX is an amzing achievement with a case that is WR to 12,000m and movement to 5,000m
The Sinn Lume is good - Omega and Seiko would be better - better, but its extremely usable
Ball - I don't know they've just never impressed me in their overall finish, so having gotten close, researched, played with it in the AD, I've always ended up walking away.
To me they seem to have lost their identity and are now a brand that is dictated more by corporate marketing nicjes than any true brand identity with too much being asked for a fairly common movement and too my eyes, nothing-special case.
Maybe I'm just cynical and let that colour my choices too much, as I'm sure that all the big and not-so-big players do similar tricks.
Tritium tubes are nice, if not as initially bright as Superluminova, but there are better-lumed Tritium dive watches for less than both - have a look at Deep Blue's range.
The down side of my Sinn's is the german u-boat steel they are made of means they are heavy particularly for their physical size.,That said the clasp is also heavy so they are well balanced.
As mentioned, you will need to send the UX to German to have the battery changed, as the oil needs to be replaced and resealed at that time
As Divers go I like the Sinn range and they're not unwearable with working attire
Ultimately its your choice, but my Sinns have proved indestructible and that is 4 years and counting.