You win this time, Seattle. The Seattle Times found that their city spent more per person on capital expenses than Denver in 2015, but only by about $26.
The data from the Federal Transit Authority captures the Denver urban area in full Fastracks spending mode. Per person, that meant $366.72 in capital expenses.
The Seattle Times further notes that Denver has completed 100 out of 122 mile light rail system, and is perhaps winding down. Seattle voters, on the other hand, approved new rail investments that will increase Seattle's margin of transit spending.
Plus, expanding the Seattle system sounds particularly costly. Here's what the paper said:
"Denver’s light-rail system costs about $8 billion, a veritable pittance compared to the cost of Sound Transit’s light rail.
"'The simple answer is tunneling,' said Mark Hallenbeck, the director of the Washington State Transportation Center. 'Denver light rail is dead flat. It’s on the road, it’s built along freeway corridors. There’s no tunneling, and therefore it’s about as cheap as you can make a line.'"