Keyboard is good. I personally would recommend bass guitar if you like rock music. If you can save up $200-300 and buy a used Squire Precision or Squire Jazz bass, it will literally last you years as long as you change the strings regularly and learn how to do an at-home setup.
You can pick up the basics and start jamming with people really fast, but the skill ceiling is deceptively high. Bassists are the hardest to find in any band.
The instrument is fun as hell too.
My favorite videos of his are his farm, cooking, and nature videos. Just a man walking through the park or feeding chickens with RuneScape music behind it. Weirdly calming.