I travelled in both, India and SEAsia.
For the first time and alone I would chause SEAsia, because its easyer to get into backpacking. I was first in India but not allone, just know that to travell in that nice country is often very stressfull and sometimes really anoying, but on the other hand its lovely too...
SEAsia is a really nice place to, especially Myanmar and Laos which are a adventure too and as nice and special than India is. Myanmar would by a great mix of indiean, thai and chinese influens a real great spot! But not halfe the hassle from India as well as high respect from womens.
I would go around Thailand, Myanmar, Laos and Cambodia. Go to India at your second travell when your expiriance is biger