(FORTUNE Magazine) – REPUBLICAN SENATOR Bob Packwood and ultraliberal Democratic Senator Howard Metzenbaum don't have much in common. But they share one dubious distinction. When a score of Washington's most influential business lobbyists were given promises of anonymity and asked by FORTUNE which legislators they fear the most, Packwood and Metzenbaum were invariably mentioned. Among others who make the lobbyists quiver: House Energy and Commerce Chairman John Dingell, Senate Majority Leader Robert Dole, and Dan Rostenkowski, chairman of the House Ways and Means Committee. The word business lobbyists use most frequently in describing Packwood, the new chairman of the Senate Finance Committee, is ''unpredictable.'' He's a big supporter of tax breaks for fringe benefits, including incentive stock options. But he went along with the women's movement and backed unisex insurance rates over the insurance industry's objections. Metzenbaum is predictable--business lobbyists know he'll oppose them at every turn. Lobbyists describe him as ''obnoxious,'' ''antagonistic,'' and ''philosophically paralyzed.'' The committee John Dingell chairs has jurisdiction over trade matters, the environment, financial services, and telecommunications. He exercises almost total control (FORTUNE, February 18). Mentioned nearly as frequently as Dingell are two of his subcommittee chairmen--Timothy E. Wirth and Henry Waxman. Handsome and Harvard educated, Wirth chairs the telecommunications, consumer protection, and finance subcommittee. Lobbyists describe him as ''smart'' and ''arrogant,'' but they are not impressed with his ability to push through legislation. Says a lobbyist for a television network: ''Wirth is just a windbag.'' Still, he's troublesome because he gets a lot of press. Waxman, the Hollywood Democrat who chairs the health and environment subcommittee, is feared because he can get things done--things the business lobby doesn't want. Ways and Means Chairman Rostenkowski is feared mainly because of the leadership position he holds. As one lobbyist explains, ''Wilbur Mills used to be known as the powerful chairman of the Ways and Means Committee. Rosty is known as the chairman of the powerful Ways and Means Committee.'' But he's known for his formidable legislative prowess. ''He can fillet you in a mark- up,'' says one lobbyist, referring to the working session that usually precedes a committee's final vote on a bill. Defense contractors lob grenades at a group of so-called military reformers who, among other things, have embarrassed contractors with revelations about $600 toilet seats and $180 flashlights. Their prime targets: Senators Mark Andrews and William Roth, both conservative Republicans. Senate Majority Leader Dole is no longer as feared as he was when he held Packwood's position, but lobbyists worry about his long memory. Banking lobbyists are still wary because they beat Dole in 1983 on the issue of whether banks should withhold money for taxes. Says one: ''Dole has yet to extract some blood.''