I'm kinda new (returning player from 2015ish), and I leveled up a new thief using the Rampager set because it's relatively cheap (exotics). So, full glass (precision, power, condition) -- Deadly Arts, Critical Strikes, and then either Shadow Arts or Trickery. Thief is the only class that I clicked with. I'm not doing dungeons or fractals or zerg wvw, so take this with a grain of salt. So, I guess the hardest pve content I do is solo champions and I try to limit wvw pvp to just me vs 1. I'm not in a guild. I don't party with anyone.
I found that p/p and p/d are the only weapon sets that are really usable due to how much more initiative efficient they are when compared to all the others, p/p is the most efficient (and you can self buff to 25 stacks of might fast, which benefits both weapon damage and condition damage) with p/d coming in 2nd place. So most initiative efficient is p/p in both weapon swaps and Trickery to keep initiative up to spam unload forever, but I prefer p/p and p/d with Shadow Arts just to keep it somewhat interesting.
The most FUN is weapon swapping between d/p and p/d due to the at-will movement options, and I actually leveled to 80 that way (after dropping d/d and never looking back). But d/p damage is... not good, and you can't just blind-tank harder pve content.
I don't like shortbow because Infiltator's Arrow uses too much initiative and the range is only 900. Just my opinion.