Unless you have a good idea how much you use, it’s going to be hard to pick.
If you’ll be on your company plan for a bit longer, you can reset your data (settings -> cellular -> reset statistics) and track it for a month.
Unless I’m traveling, 500mb a month is plenty for me (I’m also on WiFi most of the time and don’t stream). When I do travel, I can add more if needed for a couple bucks. I don’t mind paying attention, but some just want to pay more every month so they don’t have to think about it.
The nice thing about MVNOs is you can try a plan and change if it doesn’t suit you. I’d wait on the yearly plan until you know what’s up.