You should level up your account first, since at your level items tend to go obsolete fast, so at your level I would not worry about which pro set is best.
When you buy items now at hero level 60, they will definitely be obsolete when you are around level 70 (around level 111 you can start to buy your permanent ones). Check the rarity of those items, when they aren’t 130, it’s really wasting crystals.
As soon as you become hero level 110+, you gain items with rarity level 130, but still it means that as long as you haven’t reached level 130, that your stats will improve, but that you can then overcome by forging those stats instead.
It depends what your intention is, but don’t focus on a special set, but on more important stuff that helps you now. What do you want to do? Level up faster? Then xp items might be a good investment. Do you need more troops, then look for leadership items. Do you want to fight wars, then skull gear might help you.
Depending on difficulty and your progress in dungeons and other factors, other spells and troops might get more important. For example now you use lasting spells (Spells that last several seconds), but later sometimes instant spells (those deal immediately all damage) can also become more handy. When you for example face stronger towers, a monk can undo your damage from lasting spells, but when an instant spell immediately destroys a tower, this can’t be undone (of course the tower must go down then, otherwise it can be healed).
Summarizing, at the moment I would not worry too much about items. When you can get an item pretty easy and you benefit from it now, it’s fine. But realize they will become obsolete and need to be replaced by better versions later. So when you for example want to level up faster, it might be worth investing in xp gear. When you need more power now from your sonic blast spell, it might be good to buy an item that makes it stronger. Point is, that you are aware that those items will get obsolete. but as long as you benefit for a while from buying such gear, it might be worth the investment.