Comparing Lapras and Kingler (Krabby's second, and final, evolution), Lapras excels as far as HP, and also has pretty decent special attack and defense. Being a dual-type, it has a number of weaknesses (electric, grass, fighting & rock), while Kingler only has a couple (Electric & grass), but Kingler's HP is quite low. It does, however, have a great attack stat, and good defense as well (all other stats are on the low side). Personally, I'd probably go with Lapras, but if you just want a good water-type, you should also consider Quagsire (average stats, but has complete resistance to Electric moves) or wait to catch the Red Gyarados at the Lake of Rage.