Great question, Miche! Which house system to use tends to be a hot issue among astrologers, with many different opinions. I've been practicing astrology professionally for about 10 years and always used the Placidus system (because that's what MY teacher used). But recently, after reading some convincing articles about the Whole Sign system, I've started experimenting with it. Like you, in my own chart not much changes when I switch systems, but I've found it really useful for clients who were born far north - in the Placidus system they end up with a few giant houses (where all the planets tend to congregate) and a lot of tiny houses - making for a not very interesting reading. When I switch to the Whole Sign system, the charts seem to make more sense. I'm still using Placidus for most charts, and not yet convinced to switch entirely to Whole Signs, but I'll keep experimenting and see.
I do think that it's worth considering planets on the cusp as belonging to both houses. In my own chart, the Moon is in the 11th but on the cusp of the 12th, and it's been helpful for me to consider both possibilities (and both placements make sense to me). Astrology is really a process of discovery - with other people's charts, you could explain the meaning of both house positions, and see which one resonates more for them (or if both do). My suggestion for you would be to play with both Placidus and Whole Signs (and maybe even other house systems...) and see which one feels right to you.
With so many options for drawing up charts (tropical or sidereal zodiac, which house system, whether or not to include asteroids, etc...), it really comes down to what resonates the most for YOU. While some astrologers feel very strongly that one system is right or wrong, I think (true to my Gemini Rising) there's validity to all approaches. Best of luck to you in your astro-studies!