For learning as a HR Intern, please dont look for best companies. Such companies may not teach you everything. Even one can learn from bad companies as well. Much depends upon your mindset and attitude. Learning is done in any environment. You learn the DOs and DONTs simply by observing things happening around you. You learn, observe and absorb all good things and remember to leave out all bad practices. Ensure that you do not follow the bad things. That is good enough for you to come up in life !
Best wishes