Few anime hold a lingering place in my heart and mind. Free! is one such anime. Now a veteran series (begun in 2013), Free! tells a story about friendship, dedication to goals and triumph over adversity. There are plots and subplots, characters both major and minor that grab hold of one's psyche and a finale that satisfies.
The only thing that detracts from the series is the insistence of some fans to tout romantic relationships between characters when friendship is the only thing that matters in the world of Free!, the strongest bond being between Makoto Tachibana and Haruka Nanase, best friends since childhood. Kyoto Animation steered clear of creating a BL story but, instead, embedded hints throughout the series so fans could make up their own minds about such things.
In 2013 and 2014, a rivalry existed between those pairing Makoto & Haruka (Makoharu) and those pairing Rin & Haruka (Rinharu) as a romantic pair, but Kyoani wisely failed to resolve the issue in canon. Smart move, Kyoani. I just wish Google followed suit instead of allowing fanon answers to serve as official answers to questions posed by those who do not know the series. If you are one such person, know that none of the characters are romantically involved.
Other than that, I recommend the series whole-heartedly if you're looking for a series that provides smiles, laughs, a few tense moments and a few tears, too. It is exemplary.