To answer the original question, though...
Dingir has "many tropical islands", although imported Terran flora and fauna have supplanted a lot of indigenous lifeforms -- so there might be additional reason for collectors and preservationists to establish habitat replicas elsewhere. A bit of goodwill (and funding) from conservation efforts on the side? Also, everyone in the sector will have heard of Dingir, it has a pretty important history so should be automatically a talking piece.
Khedish has "evolved a complex ecosystem". The world's environment is harsh and changeable, so there might be many interesting adaptations and behavioural forms?
Kasaan has a lot of wilderness and complex native life; the Jabberwocks are from there. No doubt other equally beautiful but less dangerous lifeforms are present. The tulgy woods of Kasaan are surely worth reproducing? My uffish thought for the day.
Noricum has "over a million distinct species of aerial animals" and floating forests over parts of its ocean. Thick atmosphere and low gravity, so maybe some sauna-type recreation sphere with attractive and harmless flitterers all around?
Gaea would be obvious, what with its super-dense and very old biosphere. Might be hard to keep it healthy, what with all the symbiotic links between its species, but then anyone who could pull it off would be quite admired. Perhaps it's a point of pride to those in the business to keep the most complex Gaea biome you can, and compete as to whose is more integrated and has a wider web of species?
