Thanks for the help guys. I prefer 2v2, I avoid all the others
I have a similar issue when deciding between the two Assault Gren doctrines. I prefer regular tiger (it's also less embarrassing if you lose it compared to Ace), but I like the halftrack stealth a lot.
The key to using the Tiger Ace is spamming its abilities. The super repair ability means it never has to stay idle getting repaired for more than a minute if you have Pioneers to help, which means it can be into action more often. You should basically spend all your munitions on that once you get the Ace.
Once it hits vet 2 - which happens quite quickly because it comes at vet 1 - it easily becomes the strongest tank in the game. It gets the +5 range bonus of vet 2 and allows you to activate Spearhead mode which barely has drawbacks and allows it to suppress infantry and selfspot.