In terms of just obtaining the platinum, there's a couple of positives and negatives regarding either playing the base game or with DLC. Rebirth you only have to complete 20 challenges for the challenges trophy, instead of all 35 in Afterbirth +. There are less requirements to unlock godhead in rebirth, but the added holy mantle in afterbirth makes the character much much easier, and imo makes it a fun character to play as. Two secrets, super meat boy and bandage girl are MUCH harder to do in rebirth and are made significantly easier in afterbirth / afterbirth +. What I did as I played the game on the Vita and had done everything bar the super meat boy and bandage girl secrets was get as close to 100% as possible then import save into afterbirth + to get remaining items and secrets. Greed mode makes it much easier to get remaining items as it is very easy to break the game in that mode and get close to all items. I did the lost in rebirth but you would be able to do it in afterbirth, just with more steps (donating to greed machine as well as beating greed modes and hush, delirium and mega satan). Hope this helps!