This depends greatly on what type of work you are doing and how often you are doing it.
In general, if you only need to drill a few holes, we recommend going with the Plated Core drills. They are more versatile in the sense that you do not need a center water feed, and you do not have to use them in a drill press if you don't want to. They are far more forgiving of being out of alignment with the hole you are drilling and will withstand more abuse before breaking.
On the flipside, they have far less longevity than a Sintered Core drill, so if you are looking at drilling many holes for a extended period of time, a plated drill will end up driving you crazy.
Sintered Core drills have several layers of diamond throughout the entire tip of the core drill, so as it wears down, you can run it through a dressing stick and expose new diamonds. This extends the lifespan and usefulness of the drill significantly over the plated drills.
Of course, with that softer metal tip on the sintered core drill, that also means it really requires a center water feed (another up front cost) and use in a drill press. You can use a straight shank adaptor with the sintered core drill and use it handheld without a center water feed, but you run the risk of ripping the diamond tip off the drill if you're not very very careful.