Animal Companion help

Hi all,
I've never played a character with an animal companion before and need some advice. Which is more effective, a normal animal companion with bonuses due to the druid's class level or an alternative animal companion? (for example, would a 7th level druid's Wolf with +4 HD, +4 AC, +2 Str/Dex, 3 bonus tricks, link, share spells, evasion and devotion be more or less effective than a Dire Boar with +0 HD, +0 AC, +0 Str/Dex, 1 bonus trick, link and share spells?)
Thanks!

Well, on a purely mechanical level... the alternate animal lists are more powerful.

But you may have trouble walking through town with a Dire something... where as no one would give a second glance to somebody walking around with a dog or a horse. An advanced initial companion looks the same!
YMMV

Mike