I have two 2GB N2s that run quite happily with CE. I have one 4GB box that I bought on the chance that the extra memory would useful for EmuELEC. The 2GB boxes run CE without issue.
The N2+ is slightly beefier on paper than the C4 and has a slightly newer processor, S922X on the N2+ vs S905X3 on the C4. This may make the N2+ more future proof.
That said either would be good choices. I use emmc storage on all of mine, and if you choose to go that route get the SD module so that you can easily flash the emmc.