This seems to be a rhetorical question because normally you don't have any control over last three points. But the full charge-discharge cycle would be the worst strategy.
Practically every smartphone has an intelligent charger that follows the standard charging procedure for Li-Ion batteries: first it applies constant current until the voltage gets up to float voltage (4.20 V for regular Li-Ion, and 4.35 for Li-Po cells), so-called constant voltage stage. Then the charger sits at this voltage level while the battery sucks the full charging amperage for a while. Then the battery (by itself) begins to reduce its current. At this point the battery recharges about 80% of its rated capacity. The dropping current indicates the final charging stage. Chargers usually terminate (disconnect) when the current drops to 1/10 of the rated charging current.
If battery is not loaded, the charger would wait until the terminal voltage drops by 100 or 200 mV (by itself, due to self discharge or some sleep-mode consumption), and will kick off a new charging cycle. But since the battery is already charged to the top, the voltage will rapidly rise to 4.2V level, and current will be already low, near the termination threshold, so the cycle will be fairly short, few seconds maybe. Then the cycle repeats. It is sometimes called "trickle charging". Modern charger ICs do this autonomously, without SOC intervention.
For the good lifetime for a battery it would be better to terminate the charge right at the beginning of the current drop, or at something like 20% drop. It will save the battery from overcharging electro-chemical effects and prolong its life. Theoretically a SoC can adjust charger parameters, but it would be a challenge to find and alter the kernel code for this.
The fast or slow charge also can be controlled via computer interface, at least in most Texas Instruments ICs. So if you have an access to charger configuration, slow charge will also help to maintain good SOH - State of Health of the battery.
In short, keep it always connected, don't do deep discharge cycles, reduce charge current if you can, and rise the termination threshold to maximum if you can, and you will be fine.