In some ways, that’s comparing apples to oranges.
Seiko competes in many different market segments, including relatively inexpensive quartz and mechanical (Seiko 5) watches, all the way up through the mid-range and even into the high-end (Grand Seiko), where they are a competitor to Rolex. Comparing a Seiko to a Rolex, therefore, depends on which Seiko you are talking about.
Rolex deals in a high-end market segment, although they’re not as high-end as Patek Philippe and some other big-ticket Swiss brands. They have a lower-cost product, which uses ETA movements (instead of in-house Rolex calibers) and is branded “Tudor,” but even Tudor watches cost more than the vast majority of Seiko products.
From the standpoint of quality or aesthetics, there’s not much difference in a good Seiko and a Rolex. I’d rather wear the Seiko SARB017 Alpinist, which sells for $430 on Amazon, than any Rolex:
In terms of quality, Seiko’s is so good that a few years back, TAG Heuer licensed a Seiko chronograph movement, made a few minor changes to it, andbefore they were called out on it. If a famous Swiss watchmaker thinks Seiko’s stuff is good enough to pass off as their own…
The advantage to a Rolex, of course, is that in addition to being an excellent watch, it is a status symbol. Even the best Seiko watches in the world don’t have the same cachet as a Rolex, even if they are arguably superior in design and/or engineering. It’s still not a Rolex. And while I wear watches for my own enjoyment and not to impress anyone else, having that “Rolex” name does matter to a lot of people.