I'll throw in my $.02 on the 3 in 1 option. Oldred is right about 3 in 1's being a compromise. But of the Mill/Drill/Lathe functions, the lathe is the best function of them. The bed is decent length and there is enough area to turn larger items. There are larger chucks available also. As far as accuracy, they can be very good when they're set up properly. Factory dials are usually in metric, and useless. I've mounted digital calipers to the table with very good results. The mill is useful, but you are very limited in height adjustment and table size/travel. I've used my MDL many many times and for a lot of us, there isn't enough room or demand to have separate machines.
Check this site out for machine tool info. http://www.chaski.org/homemachinist