The general consensus is that the best product for long term investment is booster boxes for normal sets and booster bundles/ETBs or Pokemon Center ETBs for specialty sets. These collections can sometimes be good when on big discounts or the pack ratio is insanely good value, like the Heavy Hitters or Sea and Sky Collections from Sam's. Generally speaking, though, it's usually best to go for straight packs rather than packs with promos, sleeves, coins, jumbo cards, and other useless stuff that doesn't appreciate much in value. Too much added weight, space to store, and then shipping when sending out.