Maybe. They do also come in various design patterns, so cosmetics won't be too much of a problem. Still, if I was to pick one to defend myself, I'd choose the Sentry.
Sentry goin' up!
Now, I won't say that the Turrets aren't ineffective. They're just not as effective. Still, there is strength in numbers. You know what? I'll get Fluttershy a few with a Sentry as an added bonus. The best of both as it were.
That works! The turrets are there not necessarily to stop the enemy, but they can be used to lure them into a false sense of security. That way, whoever approaches doesn't expect there to be anything beyond the turrets and is caught off-guard.
I'd go for the TF2 sentry. Why? Because the level 3 sentry has GODDAMN MISSILES! those Portal turrets only have the limited visual on their targets, the sentry can rotate 360 degrees. push and tilt over the turret can defeat it that's whimpy. The level 3 sentry can take it like a true machine. It can lose health when being attacked and left unattended but that is how a real machine functions!