It depends on how you ride.

Here's what I bought for my commuter: https://www.target.com/p/schwinn-fra...p/-/A-14787924
It's an inexpensive Schwinn frame pump with a toe-hold and a gauge. I bought it in-store at Target for $14and it looks like they have it online for $8.

It has lasted me 2-years.

I need a gauge for 2 reasons.

1) My AirZound Airhorn. You can't estimate the PSI by squeezing the cannister, especially the newer metal ones (vs plastic)

2) Studded snow tires. I run them 55-65psi on dry pavement, ~36psi on ice and ~25psi on loose snow. It really makes a difference.

I had originally carried a separate gauge, but that was too much trouble to attach the pump and inflate, remove the pump, use the gauge, attach the pump again, etc. It is so much nicer to just pop on a pump with a built in gauge.

If weight-savings and minimal gear are your thing then CO2 cartridges are for you. If you don't mind adding weight for convenience and versatility, then a frame-pump is for you...and one with a built in gauge of adequate accuracy is much faster and more convenient than a separate gauge.