I have heard good things of Attitude, some soso things about Nirvana, I havent used either one. I use marijuana-seeds.nl came highly recommended by some heavy hitters on this site and I once I used them, I was SO impressed. stealth shipping included in regualr $5 shipping cost, arrived in reasonable time and I ordered 30 seeds, got 3 feminized free, out of the 30 28 germinated and turned to seedlings, all 3 feminized germinated and growing quickly. great strains available, good pricing and very helpful info on each.
my .02