Another template, another iconic monster. Right now, lycanthropy are kind of suboptimal, as every one of them will be eating +2 or +3 LA in addition to the (bad) animal HD they'll get.
Lycanthropes gain a number of animal-independent bonuses, such as +2 wisdom, scent, low-light vision, some natural armor, Iron Will for free, and DR/silver. This on its own seems to be a strong +1 LA or weak +2.
The animal form adds to this Lycanthropic Empathy, the animal's special attacks and qualities, the animal's feats, and possible physical ability score adjustments/size changes in hybrid or animal form. This is counterbalanced by the lycanthrope getting all of the animal's HD as well.
Note that for melee combat, almost all PCs will be getting RHD. The only medium-or-bigger animal I could find without multiple hit dice was the baboon: something that doesn't seem too powerful.
Honestly, I think +1 LA is fine for natural lycanthropes. They'll all have at least two HD of non-great types: they don't need a giant LA worsening their situation.
Afflicted lycans, while possibly able to get away with less HD, also suffer a number of drawbacks naturals don't have. +1 LA works there as well.