"Pad" was met with extreme derision by female tech journalists, their "me too" male counterparts and anyone on Jezebel.

I'm sure Apple's brand is strong enough to overcome the current connotations.

So go with Lion, Mountain Lion, Lynx, Serval. Then it'll be 5-6 years from now and either the slang usage of "cougar" will fall out of use or at least the novelty will be gone and people will interpret it as an allusion to the cat itself.