BERT: Encoder is all you need. Also, left-to-right language modeling is NOT all you need. (Also, pre-training + finetuning 📈) https://arxiv.org/abs/1810.04805

T5: Encoder-only or decoder-only is NOT all you need, though text-to-text is all you need. (Also, pre-training + finetuning 🚀) https://arxiv.org/abs/1910.10683