Google's Flan-T5, Flan-UL2 and derivatives, are so far the most promising open (including commercial use) models that I have tried, however they are very "general purpose" and don't perform well in specific tasks like code understanding or generation. You could fine-tune Flan-T5 with a dataset that suits your specific task and get much better results, as shown by Flan-Alpaca.

Sadly, there's no open model yet that acts like a Swiss knife and gets good-enough results for multiple use cases.