What's the most sweetest language in this world...? 

Undoubtedly, everyone will say and claim 
that his/her own native language or 'mother-tongue' is the most sweetest language in this world!

To me too, TAMIL is the sweetest of all...!
(as I don't know any other language, other than little English) 

I'm not a linguistic scholar, 
but I know almost all the 
'good, bad and ugly' words and sentences 
in Tamil and in English.

In Tamil, I used to speak 'Kongu Tamil', 
as I born and brought up in Coimbatore. Coimbatore Tamil accent will be easily distinguishable by other Tamil speaking people. 

AghilhaM wholeheartedly wishes all Tamil speaking SWEET people, living all over the world: 
"Iniya Tamil Puththandu Nalvaalththukkal." 
("Sweet Tamil New Year Good Wishes.")

Related reference links:

About Tamil New year by Tamil Canadian Services

Ethnologue Report of Tamil by Ethnologue.com

Tamil Language Profile by LMP.UCLA.edu