Hello,
Reference your query, I feel what's important is your own interest.
First you think to ask yourself, are you interested in handling legal, IR, Labour welfare causes. If you have the aptitude and time for it, then you need to ensure you're in a job profile as an HR generalist where you can apply the learning. If yes, to all of the above, then you should pursue Law, but remember its a 05 yr course. So once you make up your mind, keep you goal and be time ready. Post this you're main industries will be where the is a large concentration of Blue collar employees .
However, if you're interest as an HR generalist lies in area of employee engagement, compensation/benefit, Talent acquisition, OD, Employee life cycle; then you may consider a Diploma in Labour laws and concentrate on working in relevant Job profile with training in the field of interest. Here you have a wider range of industries and profiles you can handle. Moreover the knowledge can be acquired thru short term courses as well.
Either way I feel an HR professional with any specialisation, should have at least a Diploma in Labour Laws, because none of the areas can be operated independently without at least basic knowledge of the regulatory framework within which you are required to work.
The choice depends on your preference and ability to dedicate the required time line. Best wishes for whichever field you choose..
Warm regards,
Deena Jagasia