I think a big part of malling is just enjoying the category you stock. For me Training and Luck is a great fit, because its relatively easy to upkeep. I enjoy malling as a part of neo but dont really have alot of time w/ school, so its a good balance for me. So thats just personal choice you might prefer the category with a larger variety to stock. I only started malling Training post keyquest, but for some reason I get the vibe its just not quite as popular as a category as it once was, considering people can earn their own stones, and battledome isnt given any attention by TNT (no plots etc). I tried to stock a larger variety of neggs at one time, but I found them HTS, although many people do have success obvi. I never stocked petpets, but i mean just the core stuff of training, dubs, faeries, stones, and scratchies are popular items so theres def profit to be made. Good luck with your decision.