You know, I hadn't realised until I read this that there were so many S4 variants which didn't have LTE!
To be honest if I was buying a phone today the Z3C would probably be my choice - I'm not interested in phablets, and it's the best spec you can get in a relatively compact form factor. The RAM wouldn't worry me, since I'm currently using a phone with 2GB RAM and it's not a problem at all. The screen resolution does mean that it will be more responsive: if you don't have a qHD screen I personally don't think you need an 805.
That said, if you don't really need a new phone at the moment then there will always be something better in the pipeline if you wait long enough. I don't know whether 64bit computing will bring a tangible benefit (as opposed to bragging rights), but if you think it will become important in the next couple of years that might be an argument for waiting for the 810. There are also rumours of a Z4 Compact with a 1080p screen, but remember that rumours are just that (Sony skipped from Z1 to Z3 in the Compacts, and the talk last week was that they would back off from the 6-monthly flagship releases, so who knows whether this will turn out to be accurate or not). If the Z4C rumours were correct then the suggestion that it would have a waterproof USB socket which didn't need a cover would interest me (flaps wear with constant use - fine with an SD card slot which you rarely open, more of a concern with a charging port). But we don't know yet.
Bottom line: have a play with a Z3 Compact. That's the best way to decide whether the screen resolution is an issue (remember that 720p 4.6" is pretty much the same resolution as the iPhone 4/5's "retina display"). Then think about whether you'd rather wait a few months in case a better version is announced in the Spring, or have the faster internet now.