Digimon Card Meta
The starter deck [ST1-11] 12/4 LV6 WarGreymon is not very popular in the current meta, mostly due to the fact that it costs a hefty 4 memory to digivolve. This means that it is extremely likely for your turn to end immediately after digivolving. This makes him a very likely candidate for removal cards such as Terra Force without him being able to do anything yet.
In some tournament decks, the other [BT1-025] WarGreymon is more often played for lower 3 memory digivolution, with <SecurityAttack+1> only on digivolution and <OptionJamming> while attacking the security. At 3 cost for digivolution, he is more likely able to check securities on the same turn, and while you also [BT1-085] Tai Kamiya this is pretty much guaranteed.
Also to note while both these WarGreymons can inherit +DP effects to almost guarantee survival during security attacks, only the [BT1-025] WarGreymon can jam security option cards. In most decks removal options are usually played at maximum copies, so there is a 50% chance of checking an annoying option such as Gaia Force or Hammer Spark.
To be honest the only true drawback of the ST1 WarGreymon is its 4-cost digivolution. I would've scored it 4/5 if they lowered his digivolution costs. He most likely cannot even stay on the field long enough to digivolve into Omnimon (if you have him)!
Competitive value: 2/5