which class has the best shortbow that i can use in pve and pvp?
thief, ranger or renegade?
They all have their place.
It is almost required for thief (or so many people say).
Rangers is mostly outclassed but some still use it in wvw.
Don't know renegade well enough to comment.
Context is important.
Thief shortbow wins hands down for utility and PvP/WvW.
The others shine more in PvE. You can make Ranger shortbow work in PvP and WvW, but it is outclassed by other options in that regard.
I mostly use Short bow on ranger as a primarily PvE player who loves condi builds.
Thief for conpetitive modes.
Ranger for PvE.
Renegade also mainly PvE but more difficult to master than rangers.
SB as a weapon or as a tool? I can't speak for every class but in case of thief:
It's a great tool for moving around thanks to skill 5 but it generally fails as a weapon. Skill 4 is usable for condi builds but the power option (skill 2) fails completely thanks to how impractical it is from a gameplay point of view (the damage is also quite bad). Skill 1 and 3 are ok(ish) I guess but nothing special either. It's definitely not a good weapon set which is why you almost never see anyone use it aside from tagging stuff and moving around.
i play renegade, visually is incredible, but the gameplay you do not feel complexity, you feel just spamming skills.
"It's a testament to the folly of the humans and their gods. They say Arah was sacred, but all I see is one big dragon nest."(Rytlock Brimstone)
Thief. Has mobility, has evade, does a significative amount of damage and has good utility tools (stealth).
Thief because I am biased and the dreamer is awesome on a thief
Renegade SB is crazy fun, tons of AoEs.