Generally speaking, CPUs do not have high failure rates unless you abuse them. With proper cooling (stock cooler is usually enough) you should not need to worry unless the fan dies or the thermal paste goes bad. Overclocking a CPU should be fine as long as you install a proper cooler to handle the extra heat and you do not excessively OC the CPU and apply high voltages.
Overall, a Core i5 CPU should last you longer than an A10 APU because at the same clockspeed, the Core i5 probably provides about 30% more raw CPU processing power. This means you will likely want to upgrade a PC with an A10 APU sooner rather than later in the future.