I used a table saw with a new Forrest Woodworker II thin kerf 10" blade. This sawblade is awesome - feed as fast as you can and still get very smooth cuts. Put featherboards on to both hold the board down as well as in towards the fence. I used two roller supports behind the saw and two in front of it at about 6 and 12 feet away and was able to rip 18' boards by myself with no problem (set it up in the driveway so it fed slightly downhill and the outfed pieces pretty much rolled out themselves). Radial arm saws tend to have far more kickback problems and also tend to oscillate more unless you have a very stable industrial duty one so the cut is not as smooth. My bandsaw with a 1/2" wide blade tends to wander. If you want a nice job you'd have to buy an expensive resawing bandsaw that can handle a 3" wide blade. Just my own experience - you should do what works best for you.

> I don't own a bandsaw yet, so I can't say for sure. My gut feeling
> is the same as yours (blade likes to do curves), but they do use bandsaws
> for ripping in lumber mills. If you get a chance, put in a wide blade,
> set up a long, stable fence, and give it a try. Let me know how it
> goes, I'd love to get your impression so I can gain from your firsthand
> knowledge.

> BTW, butcher shops get really good blades for bandsaws. My brther
> and my brother in law have both bought rolls of butcher bandsaw blades,
> and swear by them for thick wood. From what I understand they're a
> great bargain. They do come in a roll, which means you have to cut
> them to length and weld them. My brother teaches machine shop at a
> Jr. College, so we have access. For a small fee, I'd bet a machine
> shop would do some for you.