Slash Keyboard for Android alternatives

I was bouncing between Swift, Google Keyboard (before they re-branded it as Gboard), tried also some other new and old kids on the block, none had a level of customization I needed OR multi-language support (including aforementioned Google Keyboard).

Once Gboard introduced two languages I had hard time choosing between a bit sluggish Swift that had 3-language support and Gboard supporting "only" two languages. Then Google introduced a simultaneous support of 3 languages and it was a no-brainer for me going for Gboard.