The lever action is excellent for drilling lots of holes quickly with no particular need for depth accuracy. A conventional tailstock provides good accuracy but slows drilling down if you're in a rush. Nice to have both.
Of the two, I prefer conventional because most of the drilling in my workshop is done on milling machine or pillar drill, and for most purposes they do a better job faster. Lathe drilling is still important, but – for what I do – a lever action tailstock isn't a big deal. It depends – others love 'em.
In the past, Myfords were often put on repetition work where accessories such as adjustable depth stops, lever tailstocks, and tailstock turret tool-holders are the bees knees. Although there must be lots of exceptions, I suspect most of us rarely do repetition work.
Order a copy of L.H.Sparey's "The Amateur's Lathe" : he describes and explains most Myford-era lathe work brilliantly.
Dave