The answer is, unless you're able to buy wholesale, there's probably not many sets that will earn you money. The market is hard to predict. But ultimately, people will buy sets with great artwork. So which sets have the best artwork?
While it's a matter of opinion and my word is by no means the gospel, there's a few key indicators that a buyer can look out for.
- What is the theme of the set?
- What are the main Pokémon of the set?
- How many alternative arts does the set have?
- What are those alternative arts?
- Does it have a trainer gallery or not?
All of these should be considered before investing. Currently, the most successful set of the Sword and Shield era is Evolving Skies. It might be your best bet if you're willing to hold onto something for 10 years. However, at $300 a booster box, that might be quite the difficult investment for most people. Opening it is also a gamble; you're either going to get $30 in cards or $400 in cards. There's almost no middle ground to be met.
Another one worth considering is Brilliant Stars. It features Charizard, easily the most popular TCG Pokémon out there, and also has the benefit of having a trainer gallery. It's also more affordable, usually around $220-$250 a booster box. By the way, we actually have some in stock right now. So if you're thinking about investing, you could purchase this set from us. The ETBs are also available.
How about Silver Tempest? It has Lugia, true. But the set itself only has one real chase card -- the alternative art Lugia. You would be far better off investing in that card rather than the box itself. That being said, prices are still affordable and hovering around MSRP at most retailers. The chance of pulling a $300 card is quite the gamble, but absolutely worth it if you're feeling lucky. It also has, in my opinion, the best trainer gallery. And remember, trainer galleries are not pulled as a rare slot. Sets with trainer galleries just feel so much better to open.
Speaking of trainer galleries, there still exists two other sets: Lost Origins and Astral Radiance. Lost Origins is the better investment of the two, but I am also partial to Astral Radiance. Mostly because Palkia is my favourite legendary. You would be fine with investing in either of these two sets. By the way, both of these sets will be in stock within a week or two, so keep your eyes open for those.
However, the absolute best set of this era will be the last one: Crown Zenith. It has some unreal artwork. If possible, try your best to preorder it and hang onto it for awhile. I'm fairly confident the boxes will be worth thousands within 10 years or so, even if Pokémon company prints it to death.
All's well that ends well. Spend responsibly.