Choose Mage Hand before anything else.
Mage Hand comes in use in dozens of scenarios in almost every adventure session:
- Disarming: Is there a weapon on the ground from a Disarm maneuver? Coordinate with your fighters to Disarm opponents on their turn - and on your turn use your Mage Hand to put the weapons out of reach up in trees or on ledges.
- Doors Concerned what’s behind the door? Open unlocked doors from a 30 foot distance so you don’t get struck by creatures.
- Chests Afraid that chest might be trapped? Touch it from a distance or open it if unlocked.
- Stealth Need to move items around behind people’s backs? Mage Hand gives you a way to float items up to 10 lbs around a room silently.
- Wards Afraid items are warded? Mage Hand them around or lift them up from the floor to stop from walking on explosive runes.
Mold Earth should not be confused with Move Earth. The limitation of Mold Earth is that for making trenches and such it requires loose earth. For many GMs, that means desert sand which means you aren’t going to get much use of that feature. The area of effect is often too small to make its Difficult Terrain that useful either. Lastly, it is probably rare that you are going to see changing the color of dirt save someone’s life.
The challenge with Mending is that many GMs don’t use any rules for wear and tear on armor and weapons. As a result, there's not always much use for this cantrip.
Too few uses in typical campaigns.
As further anecdotal evidence, in almost six months of play in a group with three spell casters, we use Mage Hand at least half a dozen to a dozen times a session. Every other cantrip (apart from damage cantrips) have been used roughly 1/10th as much.