probably all the stuff I love such as full featured mode selector, loudness control, dynamic expander, limiter, record and playback processor loops, record and playback selectors, tape monitor switch, graphic tone controls, built in 20 watt per channel monitor amps that will drive any type of head phone no matter how in-efficient they are. And will also drive very efficient loud speakers.
I liked ability to choose different equalization curves for phono cartridges and for R2R tape recorders. Built in Dobly or DBX decilinear noise reduction was great. Tape machines with heads that were optically aligned and never needed adjustment, Flutter filters and scrape filters I thought were very necessary as were machines with constant feed and take up tensions. I preferred 1/4 inch two track machines but also with a 1/4 trk playback head. I also like 1/2" machines that were 4 channel and 1" machines that were 8 channel. Three speed machines were nice. Didn't care for cassette, elcassette, cart decks, but loved Beta Hifi machines. Auto matic and semi automatic turntables are not for me either. Its a shame Stanton and Shure stopped making their best cartridges. They were a great value. Grace made some very nice cartridges, too.
Some digital is great, some is terrible, but, most of it is compromised just like analog is and was.