ronaksomani - Well, you need to formulate such query, I wouldn't say that can't be done, but what I can think of now is that you cannot combine or rather add up these factors. What you meant is something like S(ort) = K(udos)+R(eplies)+V(iews) for each post and then sort based on the sum of these, right?
Please note that the best factor to get the most active posts is the number of views in most of the cases, because people does not always give Kudos to the posts or reply too often, but if you have views, your post is reachable. e.g. In the below SS, the post circled in red has only 11 replies but 9 Kudos and has 70 Views (checked from API).
The post in green has 25 Replies but only 4 Kudos, and has 70 Views as well. The post in Blue has only 5 Replies and 1 kudo, but has 55 Views, so putting it in the formula we have above:
Sort = K + R + V
Red => 9 + 11 + 70 = 90
Blue => 1 + 5 + 55 = 61
Green => 4 + 25 + 70 = 99
So, if you go by the above formula, you should get the Green post on the top, then Red and Blue, but also note that more views don't always mean more kudos or more replies, 55 people viewed blue but only one kudoed it and 5 replied. It could have been a case where lets say the blue post had 100 views and same kudos and replies, then your score for Blue would have been 106, means it would top the list, so you see that Replies would be the best factor to consider in case you want to show most viewed list.
For this current thread, it has only 5 Replies + 0 Kudos + 56 Views and also has a solved answer, moreover, like lithium has hot topics based on only number of replies, so you can consider that as well. Remember, users will always read and scroll through your posts but won't always kudo or reply.
I hope this helps.