You are at least 1 hour away from a safe place to rest. Which spell do you ask your buddy to cast on you?
As long as you're expecting more combat in the next hour, 3 is strictly better than 1 because 1 can waste overhealing on a high roll and 3 is guarantied to give the full result of the roll. In this particular situation 2 will give the full result as well but will have a smaller result on average, so the only advantage is that part of the healing will carry over longer than 1 hour. So that choice depends a on your situation and plans.
It might help to examine some of the gameplay advantages of Temp HP. Just so we clear idea of what makes it so powerful.
The first advantage is Action Economy. Post-combat healing doesn't benefit the previous combat but the next one. In-combat healing benefits that combat but costs the healer an action. Pre-combat buffing with Temp HP costs an action, but it's an action before combat starts. That's not just free, that's better than free, because it saves the healer a combat action that can be used for something else.
The second advantage is a buffer against burst damage. Sometimes you're up against something with a really big special attack, or maybe the DM just rolls a string of crits or near max damage on a dragon breath. These big bursts of damage can take a PC from "slightly injured" to "rolling Death saves" in a single turn, before anyone can apply a healing effect. Having Temp HP that takes them above their usual max makes it less likely a PC will be downed by an unexpected burst of damage like that.
The third advantage is, as mentioned, that there's no chance of wasting a high roll with overhealing. The full result of a Temp HP effect will always be applied, so as long as you expect combat within the duration you'll get larger result in the long term with Temp HP versus normal healing.
Conversely, the big advantages of normal healing are that it doesn't have a duration or a stack limit. If a high HP martial PC is gravely injured, what they need is a lot of healing not a single Temp HP buff. As for duration, this really depends on your DM's style and how concentrated your adventuring day typically is. Temp HP buffs lend themselves to short intense periods of action, where as if you're spending half an hour traveling or exploring between encounters it's much more likely to have worn off before it's needed.
So really, both have their place, but it's easy to see how Temp HP could get out of control without all the limitations placed on it.