Microsoft OneDrive free: 5GB
Dropbox free: 2GB
Xiaomi Cloud free: 5GB
Huawei mobile cloud free: 5GB
Asus Webstorage free: 5GB
Apple offers 50GB iCloud for just 99c a month (with all the new perks), seems reasonable even for me. Most people spend a lot more more than that for coffee.
It seems my comment makes me look like a freeloader to some. I am not looking for free increase of storage from 5 GB. I was talking of iCloud Mail inbox space being tied to the whole iCloud account storage limit, which I have recently read a support document about and stand corrected.
I have 200 GB tier and apparently that is my inbox space for iCloud as well. That is wonderful. I did not know about this before today. I thought even at 200 GB, my iCloud Mail Inbox was still 5 GB.