Pretty much anything is simpler than KGW with silly analogies and magic numbers These alternatives are easier to tune and debug and I bet they are at least as effective as KGW. Effectiveness of course depends on what we want to optimize for; if the hash power can suddenly change a lot and we are left with too fast or too slow block-rate, we need to react faster and use something like these. I guess this is not very likely scenario for Bitcoin, so slow response time is fine for it.
 
I think PID-controller or EMA would be good options altcoins.