All-City Space Horse Wheel Upgrade
 

I have an All-City Space Horse and am wondering about wheel upgrade. The bike comes with unmarked JoyTech 32 hole disc brake hubs and WTB STP i19 700c rims. Not much info on the hubs. The dealer who sold me the bike suggested that the most consequential upgrade would be the wheels. I am curious about opinions for good, affordable wheels that would make a noticeable difference in ride quality. Thanks in advance.

What "quality" would that be?

I'd just try changing to a different tire when the current are worn out. Different brands, makes and models of tires can make a big difference on how you perceive the effort it takes to pedal and the bumps you feel.

How do you ride this bike? Like you are in a race to beat everyone else or just a nice ride and don't care when you get home?

Remove your wheels. Then remove the rotors, cassette, and tires(as well as tubes if thats how you roll).
Weigh both wheels completely void of anything more.

You will then at least have a starting point to compare your current wheelset with other options. If you dont know what you have, how can you know what will be 'better'?
I would be hesitant to hope for improved ride quality, unless your current wheels are wobbly and creaking or something obviously wrong like that. Ride quality will moreso come from frame design, geometry, tire size, tire pressure, and contact points.

Also, wheelsets vary from $150 to $4000. If you want some popular recommendations, you should list a budget so people dont take time to suggest wheels that are way above or below what you are wanting.

I second this advice unless the OP has wire bead tires, in which case, he should switch to decent folding bead tires ASAP, which should "make a noticeable difference in ride quality."

Post a photo of the hubs and we can provide all the info you need.

Without knowing much of anything based on what the OP wrote, I would say White Industries hubs laced to Velocity or H+Son rims with Sapim spokes and their Secure lock nipples. If you are a lighter weight rider and not carrying a bunch of stuff I might say go 28h. The handbuilt wheels are going to be nicer quality wise but may not do much else unless they happen to be lighterweight. The bearings will be better but beyond that it is really just weight that would be the biggest concern.

However a better wider and more supple tire at lower pressures will probably do a lot more than a wheelset would unless that wheelset is significantly lighter.