In Path of Exile, do you know why we run lab? The main reason is the loot! There is no special way to open chests as they are randomised every time.
Possible loot is as follows: an Offering to the Goddess, two additional Treasure Keys, Multiple maps (only in the Merciless Labyrinth and the Eternal Labyrinth), Multiple Sacrifice Vaal fragments (only drops with the corrupted item box), Multiple divination cards, Multiple currency items, Multiple skill gems with quality (silver door varients only drop level 1 gems with random quality while end of lab chests can drop with a variety of levels and quality), Multiple amulets, rings, belts and jewels, Multiple body armours, gloves, boots and helmets.
You can also get Multiple weapons of all types, 3 unique items, ilvl 84 items, items with additional sockets, quality currency chest (scraps, whetstones, gcp, chisels), chance for Lab only unique items; Chitus’ Needle, Death’s Door, Glitterdisc, Izaro’s Dilemma, Izaro’s Turmoil, Spine of the First Claimant, Viper’s Scales, Winds of Change, Xirgil’s Crank.
This will also apply to the Silver chests found behind Silver doors but with increased quantity as of patch 3.1, but these chests no matter how small the amount of loot you obtain will overtime provide more than enough profit for constantly running lab. If a key on average costs 4c and you bought 20 of them, you would only need to make 90c in 20 runs to gain a 10c profit this is obviously on the low end in fact I’m pretty sure you’d rarely see that sort of return due to the large range of drops possible.
Enchants: these generally will change every league depending on which skills are meta but generally you’re looking for skills most commonly used on the most commonly used base, so for the Abyss league; Starkonjas, Rat’s Nest, Any of the unique Nightmare Bascinets, High iLvl rare bases commonly used.
I won’t tell you which ones are good but you can tell by simply searching for the enchant and base on poe.trade if there are few listings you’ve more than likely obtained a bad one so re-roll it! Enchants while they can provide a metric ton of income aren’t reliable enough to make profit they are simply the icing on the cake and provide extra sources of income every so often.
It’s also worth noting do not waste Uber enchants on your gloves you can farm merciless lab for those, it’s a minor difference stat wise at the cost of possible multiple exalts, you can if you so desire enchant your boots in uber but I prefer to either do it in Merciless or buy the enchant myself.