The first answer can be found by asking yourself why you are wanting to collect silver coins. If you are collecting merely for the beauty of the coin and future investment consideration are of no consequence then you might just collect coins that look really nice and are slightly more expensive for the silver value.
On the other hand, if you are collecting silver coins purely for the future investment value you might actually be more interested in collecting those silver coins that are expected to appreciate in value over the coming years not just for the silver content perhaps, but also for the rarity or antique value.
Alternatively, you might even look at silver bullion in the form of silver bars. Silver bars can be seen as an investment rather than a hobby and as they are legal tender in most countries you can attract tax considerations either at the point of purchase or later when one decides to sell and possibly make a profit. In addition, silver bars will only appreciate as a result of the silver content and in line with the current silver prices, whereas the right silver coins can appreciate in value far in excess of the silver content if they are rare and much sought after.
So the reason why you are collecting silver coins is very important as it can play a major part in deciding what coins, if any, you collect.
Of note is there are some coins that could be considered beautiful and a good buy for the future. For example, Canadian Silver Maples and US Eagles come to mind. Also, The British Britannia and Chinese Pandas are examples of good quality silver coins that have an inherent beauty and should be a good buy for the future, as most experts predict these pieces to be attractive movers well into the future.
When it comes to buying a collectible silver coin ensure you know why you are buying the coin as it will go a long way to ensuring you buy the right coin for you.