Season 3 of SAO was actually pretty good, although the continuation once again turned into a Kirito harem which really dropped the quality for me.
@No0B - Log Horizon has its 3rd season releasing in January so its still going. The manga or lightnovel is still ongoing as far as I know so they are being smart and not just making up a story as they go.
Grimgar is so uninteresting and boringly generic. The visuals are cool, but as far as anime goes its not great.
If we are talking 1st seasons only, I enjoyed Overlord a lot but I think Log is probably better overall.