Which post hoc test should I use?

You are welcome. I am happy to share my knowledge with you. ^^

Thank you for this information.

There are a great number of different post hoc tests that you can use. However, you should only run one post hoc test – do not run multiple post hoc tests. For a one-way ANOVA, you will probably find that just two tests need to be considered. If your data met the assumption of homogeneity of variances, use Tukey's honestly significant difference (HSD) post hoc test. Note that if you use SPSS Statistics, Tukey's HSD test is simply referred to as "Tukey" in the post hoc multiple comparisons dialogue box). If your data did not meet the homogeneity of variances assumption, you should consider running the Games Howell post hoc test.