Proper toilet flange

I'm in the middle of a bathroom remodel and need to know which type of toilet flange to use that goes into a cast iron drain. Any sealer used? Thanks!

If you use a cast iron flange, then the lead and oakum make the seal. IF it is a 3" pipe, you can get a flange that clamps to the outside of the pipe with a neoprene (?) rubber seal. If it is a 4" pipe, you can get a similar one that clamps to the inside of the pipe. Or, you can snap off of the cast and replace the whole part with pvc. while using a no-hub conection to hold them together.

I've seen plastic flanges at HD, that have a rubber like seal on the outside of it. It looks as if the seal is slightly tappered. Apparently it just gets inserted into the pipe and the rubber seals it. Have you seen/used these?