Depends on the work you want to do. I am a gunsmith. I have and use daily a Southbend 9A lathe, and a Clausing 8525 knee mill. Both are from the 1950's and suit my needs well. But again, I am a Gunsmith and I do small work. I have run up against the size limitations of my machines many times. As jimmyjimmy mentioned DRO(s) are AWESOME to have. Everyting you want to do can absolutely be done without dro's, but is magnitudes faster and simpler with them.
Personally I will eventually step up to a slightly larger lathe with a larger through bore (my main limitation is the 3C collet system on the south bend) and a dro. Something on the order of a 10' grizzly gunsmith lathe. I will probably keep my Clausing mill always (it is perfect in so many ways) but I bought a cnc mill to automate some of what I do, (just a Chinese syil unit) and will add a full sized Bridgeport knee mill with dro capability and power feeds.
There are a TON of great machining videos on youtube and some of the absolute best are by an old shop teacher named mrpete222. Herenis the first video in a series of 3 by him on "how to buy a lathe" All of mrpete222's videos are gold.
If you have any specific questions just ask and I will try to help. There is a lot to consider, but dive in! Machining is extremely satisfying and fun!
