Support Items
Can someone explain me what item is a better choice?
+
or 
Can someone explain me what item is a better choice?
+
or 
It all depends on a situation, champion, who your adc is...
wel .. depends ... the
+
takes up 2 slots if you buy the
, you loose the execute and gold passive ...
Depends. Games are not very long anymore, so it's not likely to get full built. Some people say it's better to buy the 2 items, since you won't need the last item slot anyway.
If you are losing hard, go for the gp10/sightstone mixed variant item because you will want the extra ward earlier. You will also save money to help you get to other items such as locket which may be game changing.
If you slightly behind all the way to far ahead, stick with sightstone, finish your gold income item because you will have the extra gold to spend and will need the shield even more to protect fed carries.