Year one player here of D2- was 12 years old, now 36.
D2R in my opinion will always be superior because it gives that nostalgic feeling when I play ( possibly you too ) which makes me happy/fuzzy inside and it just makes me at ease.
D4 is a very fun, massive time consuming grind which we all seek. The game is simple yet complex, has countless build options, a long rich story line, a large amount of nm dungeons to explore and areas that give you good loot and experience. ( no chaos, baal runs here boys ).
Embrace the learning curve! Highly suggest playing D4 and sprinkling in some D2R still.
Happy gaming nerds