Even though the manual is not offered in the upper trim levels (LE, SE, GT), the 2019 ES (manual) has evolved into a nice package. Back up camera, bluetooth, six-way adjustable driver's seat, & cruise are all standard now. These were not found as standard equipment on the ES when the SE manual was offered in 2017. I would much rather have the manual temperature controls found on the ES & LE, too!
The 2019 ES manual is a nice package now even though it still lacks alloy wheels. Personally, I would take manual transmission over alloy wheels any day. Much easier/cheaper to upgrade wheels than change out the transmission on any car.
I think the 5 speed manual is a hoot to drive. I am not a small guy, & I don't find the Mirage uncomfortable at all. I've never sat in the back seats, but the front seats seem perfectly fine to me. I really wouldn't change anything about them.