The best approach is to have a very deep and versatile roster so you're adept at countering the opponents formation.

But in my opinion, if a manager is going to play an entire season with only one tactic, the best tactic to use is either 4-1-2-1-2 ND or 4-5-1 V. The narrow diamond benefits due to three things.

1. The most popular formation in T11 is the 4-4-2 classic. The 4-1-2-1-2 ND plays well against. So, in a sense the formation is countering the meta.

2. Its a push against other centric passing formations, granted 4-1-3n-2 might give it problems.

3. The best counters to the narrow diamond are vulnerable on the flanks. 3n-5-2V and 3n-1-4-2 both lack defense on the wings. There in no coverage for AML/AMR in either and one doesn't cover the ML and MR as well. Hence, if managers are running these tactics as there only tactic (especially 3n-5-2V), they're bound to run into a 4-4-2/4-2-2-2 hex/4-5-1V, problem before the late CL/Cup rounds in addition to more bad matchups in league play.

Similar can be said for 4-5-1V. It seems to play well against 4-4-2 (but I don't understand why). Defenders well against centric passing formations. And 3w defensive sets, although being useful against a lone striker have problems against formations with more than 1 ST.