Seasons are very different in terms of vibe and characteristics but my bestfavorite season is summer.

If you're using my, you should use favorite except for best, as it shows your favorite season according to your opinion.

The summer is unique inbecause it has sunlight, flowers, holidays and happy times.

This makes it a bit smoother

Although the weather in summer is very hot, weit can be fix thated by going to a summer resort.

You forgot the word is between summer and very hot, and also, who is We? Make it clear who you are referring to, as we could refer to any group of people you are referring to.

Also in summer we go to gardens and green landscapes to enjoy the summer.

Forgot "to" between go and gardens

The sSummer is unique in sunlight, flowers, holidays and happy times.

When referring to a season as a subject, we typically don't include "the".

Seasons are very different in terms of vibe and characteristics, but my bestfavourite season is summer.

Use favourite when you talk about yourself. Use best when you compare all.

Although the weather in summer is very hot, we can fix that by going to a summer resort.

Also, in the summer we go to gardens and green landscapes to enjoy the summereason.