My experiences on those sites somewhat similar to WU:
PWS = very reliable, never had an issue at their end. My history goes back to 2011. Still same features and layout over all that time. No pictures.
AWEKAS = also very reliable. They send message if my data upload is stopped. My history goes back to 2012. Still same features and layout over that time, but they did offer an optional purchase item a few years ago. Lots of worldwide users. Allows data comparison to other nearby stations. Can add webcam.
WOW = UK Weather Bureau and also very reliable. My data goes back more than 5 years. Some features and dashboard has been updated and modernized. Can upload individual pics. Gives Gold Awards
Weathercloud = have had no issues. I can only go back to last 6 months data. Very little change in layout. Can add webcam image.
WU = most used worldwide. Offers most features about my data and also weather conditions, historical, etc. Have been having lots of issues recently. Webcam is great feature but reliability close to nil.
Enjoy,
Paul