I'm in your same boat. I know Tableau 10.5 is in beta now but it is in the 1st release. They typically have a couple of release cycles so it could be a while longer for this version to come out. Plus with it moving to hyper there might be more testing within our organization prior to upgrading. So I would not hold off until 10.5.
We'll be upgrading to 10.4 as soon as a point release comes out.
Hope this helps.
We are on 10.3.1 and since 10.4 doesn't offer a huge amount of improvements I'm waiting for 10.5. I think you should wait for 10.5 unless your users are just pestering the heck outta you then go to 10.4.1.