The only machine I have prior to 1989, out of all the DMD machines, is a 1978 Phoenix by Williams.
I saw this machine when i was a 8 yr old kid, and then no pinnys for 30 plus years.
Some think it is basic, but what I like about it, is the really bright Pink Cabinet colours with some white n orange, combined with the playfields yellows n reds n whites. It feels a little ahead of its time being so super bright with all these really nice bright colours. If u can find a really nice one, with a nice backglass, they present beautifully when done up, and can be relatively cheap to purchase IF u can find a good one.
I am doing a full resto on mine, and I have bought a 2nd playfield-populated, another backglass and lots of goodies to make her like new.

It all depends on whether u want a fun project, or a plug n play purchase that is ready to go.

One of the reasons I like Phoenix, is only a few people I know on all of AP have one. Jeff-PinballHeaven, and I am not sure of who else at all.
Grab something that next to no-one else has, just to be different.
I also notice, pins of this era, sell very quickly when machines are offered up for sale, so u cant go wrong if u chop n change your mind.

Enjoy your hunt/look and decision making when the time is right.