Plant Food, Plant Health Formula and K++ are the most useful and enough for a healthy planted tank.
Phytocarb is anti-algae but should be avoided because it also ends up killing beneficial bacteria, causing cloudy water. Microlife is only used for speeding up the process of tank cycling. So I guess if you use Phytocarb, you must use Microlife to offset the loss of beneficial bacteria. But in my opinion, its a waste of time and risks upsetting the delicate balance in your fish tank, unless... you have major algae issues.
Furthermore, from a cost perspective, this pack costed me 400 bucks in which each bottle is 60ml. In retrospect, assuming only the first 3 are being used, then its cheaper in the long run to buy those in 220ml bottles separately.