I encourage you to play through the amps with one of your guitars. Or visit a local music store that has one of each in stock & play through it. Because in the end the amp has to sound good to you, with your guitars & your playing style.
My preference would be the Princeton. Reasons:
12" speaker is better than 8". 8" tends to sound 'boxy' and in a little amp that's already going to be an issue.
Tonal options, the Princeton has an EQ section (treble & bass). Also onboard tremolo is a nice option should you want it. The Champ only has a volume knob (which could be a pro if you want the simplest possible options for settings!).
Reverb. It's not necessary, but it adds warmth & depth. And Fender reverb in particular is wonderful.
You don't mention using pedals or effects. So I don't know if you intend to use them at all. For what it's worth, in my experience the Princeton takes pedals better than the Champ. You're already working with almost zero headroom with the Champ so putting a gain pedal, wah or modulation pedal in front of it makes it really difficult to use in my experience. The Princeton's slightly larger headroom (wattage & size), speaker & EQ makes it a little easier to effectively use effects.
Hope that helps. Happy new gear hunting!
Christopher Schlegel
Guitar Tricks Instructor
Christopher Schlegel Lesson Directory