Measuring marketing performance and understanding success isn't easy, as this article discusses very well, but there is a simple way to get a real steer on what is having the biggest effect:

Ask your prospect

Whilst they will, no doubt, have engaged with more than one of your marketing channels, something must have tipped them over the edge, so that they have that conversation with you.  The one(s) they mention is the one you record as their main route to your pipeline.

If you're a small business owner/director, this makes life so much easier. It removes a layer of data management and at least a layer of complexity; something you rarely have time for as you are already extremely busy.

I hope this helps.