It depends on the person's position relative to the cheating, surely.
For a rider, a motor is more antithetical to the sport than doping; once motors are involved it's no longer cycling as we know it, whereas doping is cheating but the basic premise of the sport of cycling remains intact. And some doping will be perceived as worse than others, too. Two particular examples spring to mind:
- taking a corner-cutting "means to an end" product such as Duval or Bastianelli taking appetite suppressants I see as more "indirect" performance enhancement than guzzling EPO. It's still doping, nevertheless.
- doping in the name of clean cycling I see as being especially fraudulent and hypocritical, which reflects more badly on somebody than just cheating. Take Davide Rebellin calling his Olympic silver medal in Beijing "a victory for clean cycling". It doesn't make him any more of a cheat than anybody else who doped, but it makes him harder to have sympathy for when he does get popped.
But for people other than riders, things surely differ. For the authorities, their being corrupt is the absolute dirt worst thing; they can't help if people cheat them, unless they are complicit in it. If people are cheating, the authorities can be incompetent in how they go about tackling that, that's one thing, but being in on it is far worse. And for team doctors, team managers etc., it differs again. The days of full team programs would seem to be passing in favour of smaller pockets and groups. Managers will often go for the "I will ask no questions, you will tell me no lies" approach, but for them a motor is worse because it's harder to spin that as a single rider going rogue, and it implicates the whole team. Who is in on the ruse affects which is worse as well. Doctors obviously have to be corrupt to be assisting in the doping practices in the first place, so for them a motor is not as bad as doping because they have plausible deniability in a motor case (and wouldn't need to be in on it). And at least a motor doesn't endanger a rider's health of course - we know of cases where doctors have been surreptitiously administering doping products as well as what was known about (take the "heated massage pads" of Liberty Seguros), which to me is worse than simply running a doping program.