Which water filtration products are less expensive vs. better: filter systems, in-line filters or filter pitchers?

Water filtration is the best solution. Filter systems in contrast to the filter pitchers have much better filtration efficiency and are characterized by a longer lifetime of their filters (up to 6 months) making their use more economical. 

Filter systems main advantage is the ability to be directly connected to a source of water, where they can produce clean water on a continuous basis. Additionally each system is equipped with a set of cartridges and spout.

In-line pipe filters installed before home appliances (POU) mainly extend their use. Big Blue® type filters with increased filtration efficiency can also be installed on the main water supply pipe (POE) thus protecting plumbing installation for an entire home.