which weapon?

[Perin]

It seams like almost everyone is in agreement that the Storm Lieutenant weapon + pieces of the storm set are the best option. However, do keep in mind that these gear pieces may not be relevant for long in A Realm Reborn.

With new content comes new equipment and if the storm set pieces become outdated, then you will be gimping yourself by taking the Storm weapon over Garuda's Beak which is reliant on you equipping four pieces of gear which may hold you back, where as the Beak will give you a good weapon while allowing you to equip anything else that appears.

TLDR: Don't throw out Garuda's weapon just yet, it may be more variable in 2.0

This pretty much. As soon as you break your set bonus, you're better off with Garuda's. For Serpents, I know this happens as soon as you get DL Helm. We just don't have as many options as Storm.

And if you're active in endgame content, you're not going to want to be using GC gear forever. A lot of people don't have access to Garuda weapons or have no interest or time to chase after things like DL gear though (not that there's anything wrong with that). For those people, Lt. weapon and GC set is the goal at the moment. It's also a very accessible starting point for people who do want to go for the rarer gear through raiding etc, especially with atomos dropping seals like candy now.