The security of your Bitcoin rests on the entropy in your seed. For this reason, I advocate rolling your own seed without trusting any device to do that for you. There are different methods for doing this. You can cut out all 2048 words, jumble them in a hat, and pull words out one at a time. Or you can flip a coin 128 or 256 times and convert those flips into seed words (there’s a 1-to-1 mapping between 11 coin flips and a BIP-39 seed word). Personally, I prefer to deal words using a regular pack of playing cards. I developed a system for this. All you have to do is print out the lookup table, then shuffle and deal two cards. Each two-card tuple yields one seed word. For example, drawing the eight of spades then nine of diamonds yields “celery”.