I have the Castlevania Collection, but not the other two. How are they? Both are on my wish list.
I like them both. The beat em up collection contains seven games and all feature local co-op and online co-op. The games themselves are all very good. They are all the arcade versions, and I heard that those versions run a lot smoother than Snes ports. And you get infinite continues, so you are guaranteed to finish them in one sitting if you wish, which is something that I appreciate quite a lot, although some hardcore gamers might not like that.
Onimusha is like classic Resident Evil from the early days but in feudal Japan. I only played maybe half an hour but it's pretty cool so far.
I got both games when they were on a discount and payed 26€ total, which is pretty okay in my eyes.
Gameplay > Graphics
Substance > Style
Art Direction > Realism