Your best bet is to look thru the Vintage thread
http://www.quiltingboard.com/t-43881-1328.htm
and read some of the rec's on there. I just picked up a 15-91 to try FMQ on, but there are many fans of 201's, 66's, and of course FW's.
You kinda need to decide what you want to do, do you want a treadle , an electric or a hand crank?