Yes, tough question to answer cause there's alot of things going on and alot of things to consider.
I'm going to assume you have "bonding" or a large white filling that's been discoloring over the years? A veneer can be something that can replace the filling and create a new shape for your tooth as well as new color (or one to match what you have currently).
Invisalign is a good solution to close a space possibly depending on the difficulty of the situation. But since you are removing a tooth, it may be better to move the teeth to avoid the implant and also to straighten your teeth at the same time. I would consider the veneer after the invisalign is done and you can see your smile at the end unless the color is so far off that you can't wait.
Thank you very much for your help!
The discoloration could be a cavity or it could be staining. Your dentist could polish the filling a little bit and see if they can remove the stain and smooth out the filling.
Its hard to say about whether a veneer is appropriate or not. It depends on how extensive a change you want. If its a pretty severe chip or missing part, a veneer may be the better option.
Also, if you do select to do a veneer and then get invisalign, its probably going to be okay. They will move the teeth appropriately to line them up in an ideal bite and cosmetic outcome as best they can. Your dentist should be able to predict somewhat the best course of action in regards to veneer vs invisalign first.
As for review sites, I'm not sure. What part of the world are you in? I think in the US, alot of people check the doctor's websites, yelp reviews, etc. I think the most popular way to find a dentist is to ask for a personal referral from a friend/family/coworker.
Thank you ever so much for your reply! I only have a few following questions to clarify some moments. I know that some of the tooth layers have to be removed in order to build new layers of filling. How much do you need to remove from healthy layers of a tooth in order to place a veneer? Is feeling and veneer placing comparably equal in that sense or you would choose one option over another one? And also, do you find veneers the best solution in the dental world for correcting one's smile, or there are some other great ways to correct teeth that for some reason are not perfect? Mine are missing some parts (in the inner corners area, right in the center of my smile:), so filling was really a necessity. And yes, there is some discoloration on the border of fillings and my actual teeth, and as of now you can not really tell whether it is just a color change, or caries started to develop in that lines. So I am also concerned if veneers would hold there. And last but not least, if discoloration does bother me and assuming I have placed veneers and only after that - invisalign, could it happen so that because of some slight changing of teeth positions veneers would not look as even as they suppose to? Oh, and one more thing. Is there any reliable web site that has different local dental offices reviews that you are aware of?
Thank you so much for your time and reading this letter, it is a great help to hear another professional opinion and it does help a lot to make a decision!