Ele Frontline Staff vs Dagger/x
Staff is better hands down. It offers more for team support and enemy cc than warhorn. Focus is a terrible choice for frontline. Half of its skills are single target, swirling winds isnt needed when you have reflect/aura share on demand in staff.
Bad Elementalist
Staff is better for group play, but if you want to play front line ele then do dagger/warhorn.
http://asphyxia.tv/elementalist/
^ That is my front line ele build that I ran with a couple of guilds for awhile. Worked really well but I do feel that back line ele was more effective.
Here is my back line ele: http://asphyxia.tv/wvw-back-line-elementalist-build/
Backline staff build is definitely really good. Dagger/x frontline isn’t as good unless you are in an organized group where u can coordinate heals and cc. I’ve seen focus used in top tier GvGs but no warhorn. It sucks offensively but obsidian skin on a 33s cooldown is simply too good. Note that for pug zergs anything works.