Not sure when it changed, but since my post Comcast's upload speed on lower tiers have improved.
After buying my current home, I was stuck with only Comcast for a ISP, and to get a decent upload speed, I had to purchase Gigabit service. My family only needs about 100Mbps download speeds, but for Comcast's lowest and cheapest tier option, the upload speed was only 5Mbps, which was way too low for my family.
My discounts that I got when I sign up for for the service ended this month and when I was looking for potential options, I saw that the upload speeds improved a lot, 400% faster for the lowest tier.
I signed up for the no-contract, 150Mbps download, and 20Mbps upload tier for $58 a month. Price isn't great, but it is cheaper than paying for the Gigabit service which was overkill for my family.