Some guesses:
Easily breathable atmosphere + liquid water + pleasant temperatures. Predictable weather? Mediterranean climate year round across whole planet? Entire world spanned by archipelagos, no continents (naturally condusive to smaller localised community building?) No native plants but rich soil for growing whatever plants we choose? Abundant sunlight with gentle constant breeze but few strong winds or storms? No volcanic or tectonic activity?
I'd say no pathogens but they'll come with us regardless.
Some guesses: Easily breathable atmosphere + liquid water + pleasant temperatures. Predictable weather? Mediterranean climate year round across whole planet? Entire world spanned by archipelagos, no continents (naturally condusive to smaller localised community building?) No native plants but rich soil for growing whatever plants we choose? Abundant sunlight with gentle constant breeze but few strong winds or storms? No volcanic or tectonic activity?
I'd say no pathogens but they'll come with us regardless.