Using the term 'supporting' loosely, as it's obvious most of us (Dula excepted) don't really care too much.
When Ireland aren't at a WC, I'd typically have been rooting for England. In more recent years, the Dutch, before van Persie fucked us over. Lately Germany, but they were turgid this WC.
Based purely on their game against Poland, I might be on the Colombia train this year. Choo choo.
Also maybe England, not entirely sure how I feel about them yet though. One on the one hand, Kane/Alli etc. On the other, I like Southgate and their setup is fairly wild, which is refreshing in a tournament of defensive, ultra-controlled teams.