There is not an easy answer to the question of tissue valve vs. mechanical valve.
There are pros and cons with each.
The short answer is that a tissue valve (i.e., one made from either pig or cow) usually does not require the use of the anticoagulant coumadin, but it does probably require a reoperation within some period of time, generally given at around 12 - 20 years or so, depending on your age and some other factors. A mechanical valve, on the other hand, theoretically should last your lifetime and thus theoretically will not require you to undergo a reoperation, but you will be required to take the anticoagulant medication coumadin for as long as you have a mechanical valve in you.
So either answer could be correct; i.e, I could answer your question by stating:
"Either a tissue valve or a mechanical valve is right for you".
Or I could also give you the quick answers:
"A tissue valve is right for you."
"A mechanical valve is right for you."
In all three cases you would have a quick answer to your very short question that is perfectly valid:
"Either a tissue valve or a mechanical valve is right for you".
"A tissue valve is right for you."
"A mechanical valve is right for you."
So, you have three answers to your one question, all of which are valid answers.
Even though it is confusing, I think you need to do more research and weigh the pros and cons of both valve types. Then look at your own situation, how do you feel about possibly having to undergo a reoperation versus having to take the anticoagulant medication coumadin, etc. Then, if you still have question(s), come back and ask. If your question is on valve types, you should post it in the "Valve Selection" portion of the website. Also, I recommend that you thoroughly read the "Sticky" called "Famous Tobagotwo Writings on Valve Selection" in the "Valve Selection" portion of this website.
If you are still confused, you always have the option of letting your surgeon choose your valve type and/or brand. There are many on this website who believe that is the best way to do it.