I'd like to vote for pure class druid.
Considering that I'm currently
playing a druid, I might be just a
bit biased, though...
I, too, went with the Dire Wolf. My dwarven druid (whose clan was destroyed) really identifies with the image of the lone wolf, though his understanding of nature eventually led him to realize that even a lone wolf seeks out a new pack -- thus he joined an adventuring party and now calls them his pack.
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Anyway, irrelevant character blather aside, it depends on what rules you're using.
If you use the rules updates from Masters of the Wild, then Pel needs to be at least a 6th level druid or 12th level ranger to have a 6HD animal companion, as the rules update says that a travelling druid can't have more than his Caster Level in animal companions (which means a ranger needs 2x his level).
My suggestion would be to also use the ritual rules from MotW and allow a higher level druid to advance his animal companions, rather than getting new ones all the time. This is what my DM has allowed me to do...
All that said, if you go pure-class druid, here are (from an old file of mine) the stats for a Dire Wolf that has been advanced to 11 HD. Also included for free (it was in the file) are the stats of an 11HD Dire Wolf that has had Animal Growth cast on him.
Advanced Dire Wolf
Large Animal
Hit Dice: 11d8+33 (82 hp)
Initiative: +2 (Dex)
Speed: 50 ft.
AC: 14 (-1 size, +2 Dex, +3 natural)
Attacks: Bite +15 melee
Damage: Bite 1d8+10
Face/Reach: 5 ft. by 10 ft./5 ft.
Special Attacks: Trip
Special Qualities: Scent
Saves: Fort +10, Ref +9, Will +8
Abilities: Str 25, Dex 15, Con 17,
Int 2, Wis 12, Cha 10
Skills: Hide +5, Listen +6, Move Silently +5,
Spot +6, Wilderness Lore +1*
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Advanced Dire Wolf (Animal Growth)
Huge Animal
Hit Dice: 22d8 + 110 (209 hp)
Initiative: +1 (Dex)
Speed: 50 ft.
AC: 15 (-2 size, +1 Dex, +6 natural)
Attacks: Bite +26 melee
Damage: Bite 2d6 + 16
Face/Reach: 10 ft. by 30 ft./10 ft.
Special Attacks: Trip
Special Qualities: Scent
Saves: Fort +18, Ref +14, Will +14
Abilities: Str 33, Dex 13, Con 21,
Int 2, Wis 12, Cha 10
Skills: Hide +4, Listen +6, Move Silently +4,
Spot +6, Wilderness Lore +1*
Obviously, all of this stuff is yours to take or leave. If you don't want it, I can also edit it out of the post to save space in your thread.
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Final note (I swear!

): My druid's favorite trick at level 11 was to summon 1d3 Dire Lions and then cast Animal Growth on the Lions and my animal companion.
If you have prep time, you can summon more animals and cast Animal Growth on all of them; after all, at level 11 you can use it on up to 5 animals. So if I had time (and the spells) before a fight, I would summon 1d3 dire lions and a dire bear and then animal growth the lions, the bear, and my advanced dire wolf.
NASTY!