I believe you can make a pretty efficient heavy armor-wearing behemoth out of going straight Oracle with the Battle mystery. Just pick up the Skill At Arms revelation and boom, heavy armor and all martial weapons.
Yeah, but where the Oracle has to invest a revelation to wear good armor and wield good weapons, the Paladin has those already. I think the Paladin chassis just lends itself better to the tank role. Sure, once Divine Power comes online, the Oracle can go toe to toe with a Pally, but that's still counting a round of buffing up, and the Oracle still gets less survivability. The Paladin is immensely survivable on the frontlines due to excellent saves, Lay on Hands and Smite Evil (or the Sacred Shield variant, making him even better as the group tank).
I think for what I want, a Paladin with an Oracle dip is the best bet. I think I'm going to go Oracle 1/Paladin x, choose the Lore mystery (Cha to AC and Ref saves, instead of Dex! Secondary "I know everything!" role!), pick up Extra Revelation once or twice (probably only once), put a point in every knowledge skill, and ask the DM to houserule in 3.5's Knowledge Devotion.
We're getting a free 3.5 Forgotten Realms regional feat at level 1, as a little bonus and customization option. I'm thinking Dreadful Wrath, which offers a 30' frightful presence-lookalike keyed off Charisma. Sweet debuffing option, as it doesn't even take an action to activate (just charge, full attack or cast a spell - that won't be a problem!).
Finally, I'm thinking Immortal Spark. I noticed that a middle-aged Aasimar with Immortal Spark (which replaces minor skill bonuses and the oh-so-forgettable Daylight 1/day) effectively gets +1 to his mental stats for free, so I'm obviously going to take that.