There is some official Guidance
On page 285 of the Dungeon Master's Guide there is a short section on giving attunement to magic items:
Decide whether the item requires a character to be
attuned to it to use its properties. Use these rules of
thumb to help you decide:
- If having all the characters in a party pass an item
around to gain its lasting benefits would be disruptive,
the item should require attunement.
- If the item grants a bonus that other items also
grant, it's a good idea to require attunement so that
characters don't try to collect too many of those items.
To that last point we can collect a few common types of bonuses which induce a need for attunement (non-exhaustive list):
- Non-armour bonuses to AC (e.g. Ring of Protection)
- Resistances or immunities (e.g. Ring of Resistance)
- Setting an ability score (e.g. Helm of Brilliance, Belts of Giant Strength)
This isn't particularly much to go on, but from looking at the items in the DMG we can find a couple other things that tend to be coupled with attunement:
Interaction with a class feature. Most commonly this is spellcasting, where it would say: "requires attunement by a spellcaster" or specify a specific class (or set of classes).
Charges and command words. A lot of these require attunement, which has the nice upside that command words are automatically learned through attunement and having them require attunement limits the number of different resources each character can have.
Consumables don't require attunement. Despite allowing powerful effects, items like potions, necklace of fireballs, and up to Ring of Three Wishes these don't require attunement. (Related to that last one, Luck Blade presumably requires attunement because of the reroll ability and not the wish one.
I don't stand a chance to find all the "trends" myself, so I welcome suggestions from the comments.