NEW YORK — Contrary to what many media minds might have thought, it appears that consumers may pick personal computers — not cable TV — as their vehicle of choice on the information superhighway.Viewer response to some TV-based systems has been tepid; their development is being hamstrung by technological obstacles, and media companies are expected to have to invest billions of dollars before seeing any payback. “A business can make about 10 times more per viewer with online services than with the TV,” said Joshua Harris, president of Jupiter Communications, a market research company. Preliminary results of a cable TV trial in Colorado, conducted by US West, AT&T and Tele-Communications Inc., showed revenues for the system were flat. One reason was customers didn’t want to pay more for additional features beyond the services they already paid for. Time Warner Cable said Tuesday it delayed launch of its 4,000-home, so-called full-service network. And in another setback, regional telephone company Bell Atlantic Corp. and cable giant Tele-Communications Inc. last week scrapped their planned $ 33 billion merger. The American Online service, meanwhile, is growing so fast — with some 600, 000 subscribers today, nearly 150% more than a year ago — that its system can’t handle the demand.