Andy L , Apr 15, 2010; 06:28 p.m.
"Ultimate" machines are very expensive drum scanners, but for home use - for 35mm and medium format the best are the Nikon scanners (the 9000 is in theory available but out of stock everywhere...) but for 4x5 the Epsons are what you want.
The resolution numbers they give for flatbeds are... well, lies. Sure, it will spit out a 6400 PPI file, but the optics and sensor limit the real resolution to (according to filmscanner.info test) about 2300 PPI. This means that from 35mm you can get a good 8x12 print, and it goes up from there. The Nikons are a bit more ultimate than that because with 4000 PPI and good slow film you can get unreasonable amounts of detail.