Well in term of popularity I'd say Tsuna.
He's the main character and in my opinion he has the coolest techniques.
Without hesitation, it's obviously Tsuna because he is the main character of the manga.
I love Enma however, he is the copy of Tsuna. ( Apparence, power, behaviour with others)
I love both. Tsuna more I guess. Probably because Tsuna is always around an awesome familia.
Gokudera, Yamamato, Mukuro, Hibari, Ryohei and Lambo are hilarious to have to deal with in a team.
Whilst Enma's familia sucks. Julie and the Forest flame guy were cool I guess.