I remember in 2005, Cycle Sport did an issue on climbers, and they interviewed Lucien van Impe, on what a pure climber consisted of, and he talked about climbers having a natural souplesse (suppleness, which he refers to as cadence IIRC), and at the time he rated the last pure climber was Pantani, and he thought Armstrong had a pretty good souplesse, although it wasn't natural and something he worked on. He did consider Chicken in the same bracket as Pantani, but to a lesser extent and wasn't complimentary on Virenque (ie lost a bunch of time so he can get away in a break and pick up a lot of points, and that would be it). He also mentioned about pure climbers who struggle on the flat when the sped is really high (FYI I'm paraphrasing on what van Impe considered to be a pure climber and offer a different perspective when considering what a pure climber is, and not my own opinion).
I would consider Purito to be one of the best in the world on the steep uphill finishes, along with Phil Gilbert. As for Rujano, I can consider him that his climbing is really his (only) strong point but he's not quite in the league of Contador for mine, yes he won a stage at the Giro last year, but that's only because Contador let him have the win. In some ways I would put Purito and Rujano in the same bracket, climbing is their strong point, but just not as good as Contador. I also think Gadret deserves a mention in that he does well on the climbs of the Giro, but isn't much use at time trialling and got dropped on some flat stages of the Tour when the peloton was going flat out in the run in to the finishes. In saying that though, I don't think Contador can be considered a "pure climber" in the strictest definition of the word because he's too good of a time trialist (when you think back to the time trial that he won in the '09 Tour when he even beat Spartacus, and won the prolouge of that year's Paris-Nice), but I guess in today's peloton he certainly is the best climber in the world and consistently show this day-in, day-out on multiple GT stages where there is a lot of climbing.
Riders like Evans, Menchov, Ullrich built part of their GT's wins on being very good at time trialling, and even though they haven't won a GT, Klöden and Levi in my view are time trialists who can climb very well. The same for Wiggins as well (and to a lesser extent, Chris Froome).
I would consider Purito to be one of the best in the world on the steep uphill finishes, along with Phil Gilbert. As for Rujano, I can consider him that his climbing is really his (only) strong point but he's not quite in the league of Contador for mine, yes he won a stage at the Giro last year, but that's only because Contador let him have the win. In some ways I would put Purito and Rujano in the same bracket, climbing is their strong point, but just not as good as Contador. I also think Gadret deserves a mention in that he does well on the climbs of the Giro, but isn't much use at time trialling and got dropped on some flat stages of the Tour when the peloton was going flat out in the run in to the finishes. In saying that though, I don't think Contador can be considered a "pure climber" in the strictest definition of the word because he's too good of a time trialist (when you think back to the time trial that he won in the '09 Tour when he even beat Spartacus, and won the prolouge of that year's Paris-Nice), but I guess in today's peloton he certainly is the best climber in the world and consistently show this day-in, day-out on multiple GT stages where there is a lot of climbing.
Riders like Evans, Menchov, Ullrich built part of their GT's wins on being very good at time trialling, and even though they haven't won a GT, Klöden and Levi in my view are time trialists who can climb very well. The same for Wiggins as well (and to a lesser extent, Chris Froome).