(Very) Closely followed by Kyogre, Groudon and Slaking with base 670 and then
Dragonite, Mew, Tyranitar, Celebi, Metagross, Salamence, Jirachi, Latias, Latios and all 4 Deoxys forms with base 600.
Slaking and Swampert have pretty good statistics, IMO.
Skarmory has great Defenses and Speed for a Steel-Flying type, and Ninetales, with the appropriate nature, can have a fantastic Special stat [both Offensive and Defensive]