Pokemon version question

Havnt played a Pokemon game siince the first red/blue and yellow, im thinking of picking up either diamond or pearl but wondering about platinum if its similar to how yellow was like red and blue together. Question is should i pick up diamond and pearl or just go for platinum?

Personally i would go for platinum. It's slighty modified from the damond and pearl in terms of story in certain parts. More pokes in sinnoh dex and was a more enjoyable play through, also you get dialga and palkia i think not sure on that one only just completed e4. But you do catch giratina at level 47 instead of level80.

get plaitnum better story and it's just like blue and red with better graphics and 3D parts and in yellow there was 150 pokemon in plaitnum there is 494 (going by the guide book pokdex i know theres less but it includesthe shaymin forms and rotom forms)

Platinum is a complete upgrade from Pearl and Diamond. It might be like $5 more though. It's worth it.