There are 9 Switch third party games in the top 30, while the PS4 only has 7. That means that third party companies are better off releasing their games on the Switch right now.
No... that's not what it means. God Eater 3 just launched on Switch so is one of those 9 games in the top 30. Just as Yokai Watch 4 released recently.
If a bunch of third party games released on PS4 next month they'd have a high number of releases in the top 30, doesn't mean it is better than the Switch as a platform for third parties, it just means it's had new releases.
The better example would be sales of specific games that launched simultaneously on both platforms.
Attack on Titan 2 - PS4: 20.2k NSW: 25.8k
Anyway as they're third parties and both platforms are performing well in terms of games sales, Japanese Developers are better off releasing their games on both platforms.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)