Poison or Ice shot?

Poison.

both are strong enough for all content, both can be funded to the point of doing all content by running a single chaos trial and selling the key

personally I liked Ice Shot more because with Fork and Ricochet shards were flying everywhere but Poison is plenty strong too

Poison will probably work for cheaper in endgame. I prefer ice shot at high budget but difference isn’t great.

I'm running poison and really enjoying it. Make sure you get Plaguefinder gloves as early as possible, they're relatively cheap on the marketplace. They turn all damage into poison magnitude, so you don't need to worry about focusing on just +phys on your gear. I think I made it to mapping without spending more than the handful of exalts I picked up myself. Currently lvl93 and running Temples/T15 maps with almost no problems, just a little squishy but 76% evasion helps a lot with that.

Start off as poison, it's going to be the best DPS / survivability / scales nicely. Iceshot is stonks as well (running it after trying both) but i feel it's late end-game and requires better gear to really feel the improvement.

I've played both this season, and didn't really enjoy poison all that much apart from the herald of blood/plague which can be done on other classes. I've got a Ice shot deadeye now though with Cadiro's that is great fun with great damage. Poison levelling is really rough too, would probably be best to do lightning arrow.

You should follow poison crossbow build instead. Very cheap, but powerful and can clear anything. Search for crossbow Pathfinder builds.

Poison, it will get gutted in the next league so you can try it this league.

I switched to iceshot recently with a lot of extra chain and the casino quiver. 

It be very cool.