Best way to compare development activity is coingecko
https://www.coingecko.com/en?view=developerThey also have social media activity of all coins. But you always need o be cautious when you compare, since development of coins is happening differently. Best is to take very long periods of time.
Yes, this is what I also looked when trying to find out projects activity and stuff.
Obviously, there's a lot of activity in the top 10 -20 coins because they wanted to stay on that position by updating and listening to their community and they also need to upgrade otherwise there might be competition that will kick them out on the top spot.
As for the projects that OP has posted, I'm also familiar with some of them, specially, AETERNITY, ARK, DeepOnion (who would forget their airdrops on 2017? I think they started the craze, LOL) and Digibyte DGB.