The best depends on your situation. The Lilygo T-echo is fairly inexpensive and it is a complete device. You can spend less money and build your own. The Lilygo T-Deck is nice since you don't need to pair it with another device. It has a keyboard and larger screen. The drawback is short battery life. I will probably get that as my second device, since I have a feeling I will be learning by messaging myself at the beginning.