I voted Taris but I think the poll is unfair towards TSL. Seems like the comparison should be between Endar Spire and Peragus, and between Taris and Telos, respectively. Can't say anything about Telos as I just arrived there (and encountered my first bug - people talking to me through closed doors) but I hope it will give you the freedom and sidequests that Taris did. Like someone already wrote, bounty-hunting and pazaak and the like.
Peragus was a bit overlong and repetitive with hardly any conversations and way too many droids. What it did well besides that one grey droid was creating a creepy mood (music was good, station wasn't dark enough, though) and some intentional confusion for the PC. Felt a bit like the old "System Shock" RPG.
And in general, the fights on Normal difficulty are ridiculously easy. I'm playing a sentinel with an emphasis on skills and still most enemies wouldn't even scratch me. Maybe it's because I know from KotOR I how to fight effectively but still it's barely challenging even on "Hard". And I'm already level 7 after Peragus, what a rush. *g*