Tell me the reason you wanna be a Indian instead of being a Chinese. No offence, just curious.
First of all, we were never Chinese (or Indian before the 20th cntury).
As for historical links, we got historical links with both India and Tibet.
For the reason of rationality we would choose India.
1. The language problem, we donot have any language problem here. Hindi isn't forced onto us and there is no need to learn hindi if we don't want to. Same cannot be said about China.
2. Remoteness. With China, we would be the most remote region. Even tibet and Xinjiang isn't much developed, how can we expect development all of a sudden. Further, with India we are not that remote. Being on the southern slopes of Himalayas, it is geographically better for us to be with India. Most of Aruanchal is not mountaineous and have good connectivity with the valleys of Assam, while the reach the same place from north would be a hazardous task. the topography is punishing here, something the indian army knows well.
3. Cuz we have well acquainted ourselves with India and our firm believe in democracy where we choose our own leaders.
4.
It was GoI that created Aruanchal Pradesh. What you called south tibet never existed as one unit. Barring the two eastern districts, most of arunachal was ruled over by Ahoms.
Moreover, there are three major groups of tribes in aruanchal with almost no similarity among them :-
i) eastern buddhists tribes : Monpas and Sherdukpens (now boguns also)
ii) the tanis (comprising almost 80% population of aruanchal and the land area also), they were under the influence of the british but never the tibetans.
iii) the nagas of three western districts (changlang, tirap and longding) whjo again have no connection with tibet or china.
So only region that tibet may claim is the two eastern districts, where China will find the most resistance owing to fierce allegiance to the dalai lama.