That the R8 is more versatile because it can be connected, ships with Cubase DAW software and is an audio interface and control surface are not pluses in a PC/DAW-less home recording studio. The R8's on board, internal editing is limited to divide and trim. Anything more advanced than that is totally dependent on transferring the audio files to a DAW.
For tracking, either the Tascam or Zoom work great.
For Tracking and transferring files into a DAW and integration with a PC/DAW, it's the Zoom hands down.
For a home studio with no PC and DAW, it's the Tascam, no contest.