(Just answering the thread question)
In terms of talent, Kevin Pietersen, without a shadow of a doubt. Pietersen, Lara and Tendulkar are the 3 batsmen I've seen who just seem to find it utterly easy.
In terms of performance, Michael Vaughan, he laid into Australia during 02/03 Ashes, scored that century in the 05 Ashes, scored that magnificent century when he came back this summer, and as an English fan, he's a great batsman.
Only real candidates other than Vaughan are Thorpe and Atherton, but Atherton was more of a grinder, he never seemed to have that killer punch. Thorpe comes close to Vaughan, but Vaughan led from the front, he always seemed to be able to just do that bit more, and push together with the Bells or Keys, who weren't brilliant Test match batsmen but were able to push on in partnerships with Vaughan, because he stood up when he was needed. It's not something that can be shown with Vaughan, but his ability to lead with his batting was, and is immense. Vaughan isn't only a great captain in the field, he's a great leader.
I'm not de-valuing Atherton or Thorpe here, or even Alec Stewart, if our lineup had been Atherton-Cook-Vaughan-Pietersen-Thorpe-Collingwood-Stewart+bowlers in the Ashes 06/07, or in the Indian series last summer, we'd've done a whole lot better.
Don't really want to get into a debate here, I'm just doing this as a break from Coursework.
TBH, get-into-a-debate-worthy or not...
So far in his Test career, Vaughan has still always disappointed me. His 2007 was, for mine, his best season, the first time he truly fulfilled all expectations I've ever had of him. Better than 2002\03? Yes. In 2002\03 he played one very fine innings at The SCG to do more than anyone to avert the whitewash. But apart from that, I've really never thought he did much of note. His 177 in the Second Test should have been no more than 19 (in common with most of his large scores the previous summer), and his 145 at The MCG came when the game was already lost. Also, let's not forget that the bowling-attacks he scored against in the final two Tests were very weak indeed: Warne was injured, McGrath was injured, Gillespie was injured in one of them. The bowlers were the likes of MacGill, Lee and Bichel, not remotely close to the standard of those they replaced.
In 2007, I honestly feel he played better.
And Vaughan's form as an opening batsman at large - the run of luck in 2002 aside - was wholly woeful. Now then, I was never an advocate of him opening so I don't hold that greatly against him. But the fact is he wasted 3 prime years at the top of the order. And he then wasted another in 2005 when his form was awful, then another in 2006 when he was injured (obviously, not any fault of his, but a sad waste nonetheless).
Basically, Vaughan's career in 2001 was still highly promising. But until 2007, none of those promises were fulfilled, and then he wasted ANOTHER series by going back to the top of the order. Let's hope the next 2 or 3 years bring some more fulfillment. Then I'll start to consider him in Thorpe's league.
Regarding Atherton - he was mostly before your time I'd guess. He never had what some might regard as the "killer punch" - virtually none did of his time did. Bowlers like Donald, Ambrose, Wasim Akram, McDermott, de Villiers, McGrath, Waqar Younis, Fleming, Gillespie, Pollock, Walsh, all merchants he faced in their prime powers, were nigh-unkillable. If you tried, there was a substantial chance you'd not get very many. Atherton did a superlative job of scoring very well against these bowlers, and had he not played when patently unfit on two or three occasions, his record would stack-up much better.