Respected Friend!
I've studied IL while doing my MA and opted for it as an optional subject for CSS and KPPMS as well, my personal view goes in favour of HO Agarwal. Always keep in mind the background of an adviser that what level of intellectual caliber he possesses. you've mentioned a person with LLM degree so Tandon might be better for him. You should analyse your own position in terms of time, academic background etc. Anyhow, good luck!

__________________
"Success is not final, failure is not fatal; it is the courage to continue that counts" (Winston Churchill)