Good stats on Kallis. I agree he is unlikely to ever be though of in the same bracket as a Tendulkar or Lara, his stats (even those you state above) when aligned to his bowling average is a superb all round effort. That for his batting alone it is debated whether he is the class of Tendulkar and Lara, or Ponting, Dravid, Jayawardene etc, and then he has perfectly respectable bowling figures as well (270 wickets at 32.01) and 166 catches in tests is remarkable. As I say, Im no fan of his style, but those figures are damn good.
I am always puzzled why Gilchrist seems to be the almost automatic choice for any select XI's when Sangakkara has such a good average (and Andy Flower as well). I guess as he has not played many long series against the big teams is is hard to be sure just how to rate him, but his figures are good. Don't know who Sri Lanka have lined up to play, but will be good to see them over hear for the start of the summer. Without the chucker I'm not sure how dangerous their bowling is going to be.
Gilchrist always gets the nod as the one who redefined the position. Before him England may have had Alec Stewart, but it wasn't a foregone conclusion between Stewart and Russell. Post-Gilchrist it's not even a (serious) debate: the keeper has to be able to bat to a high standard.
If that wasn't revolutionary enough, he also helped revolutionise batting styles with his counter-attacking style. It showed that you could succeed in test cricket if you blasted away. He helped pave the way for Sehwag, as he showed you could score heavily if you played your shots.
I can see why he's included, although personally I think Sangakkara is a superior batsman and when he had the gloves a superior keeper as well.
Sangakkara gets left out because (a) bias against the smaller nations (and on that point Warne < Murali); and (b) he's given up the gloves, so it's a bit of a cheat to include him.
ps Jayawardene is in that second tier as well IMO alongside Kallis and Dravid.