drow or duergar for sure, but blademasters get acupuncture, they're like a maledictive warrior that can heal themselves at least once for a couple hundred hp. I suggested them over druids cause meh, druids are druids. Drow will have less hp but plenty of mana, and clerics are an attrition class class anyway, duergar you'll get some neat resistences, decent hp/mana, but you have a harder vuln to hit then say a fire giant. Keep in mind Invokers can always jet stream you, so they'll hit a duergar's vuln, there's some easy to get exotics/a quest weapon that most people have that will hit your vuln too, but those weapons are kinda weak. At least with a drow the only ones to hit your vuln with be thieves and ninjas, plus you get auto-sneak which is awesome
Edit: For the halfling thing, you don't have to worry about being bashed/bodyslammed, due to predicting, flight potions/scrolls to avoid trips and you can be a neutral, and you get all around magic resistance, which is sweet.
Edit 2: Ask Aulian about druids, he plays a good one, most druids I've fought I guess don't understand the class that well/how to gear, so I generally beat them easily. I've never played a druid though.