I'd argue Tyk is easier to extend Tyk, as they include many plugins already baked-into their OS gateway. If you want to extend Kong with some custom plugins I think Lua is your only option. With Tyk you can use pretty much any programming language to write your middleware. Gets my vote

It was messy and bloated, we had many different plugins built in different languages and couldn't share patterns and code.

Single language simplified our architecture, less plugins created less bloat, and ultimately we moved faster with Kong.

Engineers also really enjoyed that they got to learn something new and also could get into C easily with Kong as well using LuaJIT.