Im looking to play a healing class, mainly and everyone is pointing out to either a Holy paladin, priest, or druid. From your experience which would you guys rather play for an offensive healer, for raiding and pvp?
Disc priests have always been the most offensive healer. DoTs that now scale even in 'healing' gear, Mana Burn, Mass Dispel, Normal Dispel, Fear
At the moment we're suceptible to burst, but that isn't specifically a Disc Priest problem.
Durids are the avoidance healer, kiting and using CC to avoid getting pegged down.
Paladins will be strong for a while as Bubble is such a powerful defensive tool, and plate + shield helps mitigate against the huge melee burst rife at the moment. If you look at S1 Holy Paladins were the fotm and it didn't move to Dpriest and Durid until the back end of S2 once resilience and stam came up to decent levels, but after that initial period Holy Paladins became arguably the weakest Arena healing class. Maybe the HS change will help that, but I see a repeat of S1-S4 personally.
In terms of raiding, Disc Priest will have the lowest slot allocation (1 per 25man raid normally). All healers can do heroics although Paladins have the hardest time.
Shaman I don't know enough about to comment, mine got retired at 70 and was always Ele.
Life's like a salmon swimming upstream - Hard work, and sometimes you get eaten by bears.
I agree with the above poster. Disc Priest is the best way to go. I've seen a few holy priests play quite well however this may not be the play style you are looking for.
Also in terms of raiding as mentioned above you may struggle to find people willing to allow you into a raid as I have met a few people who don't have much faith in Disc Raid healing as they don't know enough about it (Or have encountered problems in the past). However hopefully duel specs (If we ever see them) will change that and all should be well.