I've owned both, like the Tikka better. But it is a lot about personal choices.
My Tikka was under 7 lbs scoped. The Vanguard is closer to 8 lbs unscoped, so there is almost 2 lbs weight difference. That alone is a huge selling point for me. I felt the Tikka was more accurate, and with a better trigger, but not by much and some individual Vanguards may be more accurate than some Tikka's The Tikka will probably be a little more expensive. Both are foreign made. Some don't like to buy foreign, especially Japanese.
Not crazy about detachable mags and feel any gun should come with at least one spare. Anything you can take off the gun can be lost or left behind. They are costly and hard to find making a slightly more expensive gun more expensive.
Mag capacity is also an issue, standard calibers are 3+1 in the Tikka, 5+1 in the Vanguard.
The Vanguard is a much more traditional looking and functioning gun. The Tikka very modern looking. This is a huge sticking point for others.
In a nutshell, both are very good. Both are very different. It comes down to the features more important to you. The Tikka suits my style better.
But in all fairness, neither is my preferred brand. I'd happily use either, but just prefer Winchester or Kimber. But they are more expensive.