The most important thing is:

Since you want to choose a poem, of course you must do everything possible to fit the theme. In this way, if it is in tune with the theme and the calligraphy is good, if you choose one of two calligraphy works of the same level, the one that fits the theme will definitely win the prize.

For example, in the calligraphy competition to commemorate the anniversaries of the Red Army’s Long March, one article is "Seven Rules. Long March" and the other is Li Bai's "The Wine Will Be Entered". Even though the level of the latter article is slightly higher than the former one, The judges will also vote for the previous article.

If it is a calligraphy competition commemorating the anniversary of Li Bai and Ruqian, then whether it is Li Bai's poems, poems praising Li Bai, etc., they will all fit the theme and be more likely to win.