both. get a mini to bring with you and a pump with a gauge to keep at home. mini pumps don't get you to your target PSI unless you pump like 500 times, which is a pain.

How do I know how many psi?

you look at the tire. it will tell you either the bars or psi required. 110 psi is something a little over 7 bars, from what I remember. If you get a pump with a meter gauge, it makes it a whole lot easier.

real talk, get a CO2 system for actual flat fixing. I can get 23s to around 80-100 psi in one quick fill. that would take a million strokes of even the best hand mini pump. run with two cartridges because you never know...I offered to donate some CO2 to someone who flatted (in the interest of getting the ride going faster, she had a mini pump) and when it turned out the tube had been pinched on the way in (another discussion) I was able to supply a new tube and also a second CO2 cartridge. I was hosed, myself, at that point, if i'd flatted, but still, overprepare if you run CO2.

+1 for CO2. The only portable pump I'd consider worth purchasing is the Topeak Road Morph.

this is like asking Imac or potato.

Lezeyne also makes excellent mini and floor pumps.