Re: What is the best bike to build to sell?
That's not a simple question, really. If you're looking at entry level motorbicycling on a budget where you pretty much want to buy the bike pretty cheap and plug a kit onto it with little additional expense then Schwinn seems like a pretty good choice. I don't know if the Jaguar is still being sold, but something with the same frame design is, I'm sure, and those are sturdy as new made in China bikes go, look good and are plug and play. That keeps the costs lower. I like older bikes, but then you've got more cleanup to do, maybe even stripping it down for a new paint job, might need new wheels, tires & tubes, maybe ad a front brake if it doesn't have one... all of which ads up quickly so that between material costs and time it is no longer a cheap bike. Unfortunately, even though the quality of the frame makes it a more solid bike (assuming it was made in the USA) most people are more impressed with a shiny wallyworld bike right out of the box... it's brand new! So, if you're going new and trying to keep the price down, look at Schwinn. The brand name still impresses even if it is no longer made in Chicago.
Someday when I grow up I will probably lose interest in toys with wheels, but until then...