The N64 controls are pretty good all things considered. The one area where it lacked was in camera controls; LOD kinda rectified that by having a free camera, but it's tied to the D-pad and as such, is pretty much useless.
I think Nightdive Studios would be perfect for remastering the N64 Castlevanias as one game. They combined content from the PC and N64 versions of Forsaken, and restored unused content in Shadowman. They also recently made Quake II a much better game than it was originally, with some nice QOL improvements. I think they could do the games justice by featuring all of the unique content from each game, including some regional variations like Gilles de Rais' voice during the final fight in the throne room of the PAL version.
That would be far preferable to me than simply slapping the ROMs on a subscription service.