Nakamichi decks have one problem: tapes recorded on them will have rolled-off high frequencies when played on other decks, and you may have some dynamic range compression. When played on Nakamichi decks, however, they will be excellent. If you are recording for others, or for your car, or if you don't want to be dependent on always having a Nak, then buy something else.
The Tandberg TCD series are all excellent, and they were for the most part much more robust transports than all Naks other than the 700 and 1000. Until the 420/440, they didn't have quite the high frequency extension of the Nakamichis, but close.
A Harmon Kardon CD491 is a very fine sounding recorder, but in general you can expect recurring electro-machanical problems.
Phil