I use the Medela Freestyle pump and it's really portable so I just have 1. It's really light and easy to use, plus it comes with a bag, ice pack, and cooler bag so I just bring it with me everywhere. My friend says though that other models and brands (like Spectra) are more powerful so I'd get more milk if I use them. But so far, my supply has met my daughter's demands using just this so I'm okay with not buying a second pump.
I have 2 pumps. Spectra S1 for home use and Spectra 9+ for outdoor use. Spectra S1 is a hospital grade pump and weighs about 1kg, but it's bulky. If you don't have to carry it to and fro, then you can consider getting one to put in your office. If you have to bring it around, then 9+ is a very good choice because it's lightweight and portable. It also has a rechargeable battery inside which lasts 2 hours on a full charge.
I have a hospital grade pump which weighs like a rice cooker, a portable electric pump with an in-built battery and two manual pumps, in case I forget my electrical pump parts.
I have 2 S1+ (1 at home & 1 in office) as its hospital grade and I hope to maintain my supply, and a S9+ (if I need to pump on training etc it's much lighter)..
I have 1 pump. I bring it to office if need to. Using spectra 9s.
thanks