I have been in the same situation 3 months ago... I wasn't able to chose between the 930 and 830! The problem was not about the money as I was ready to spend more if they had launched a 940!!
So the 930 has a better hardware...In reality, it is 2 times+ faster than the 830... However after multiple tests in store and watching all reviews on the internet, I understood that Windows phone are really fast! Really! You almost can't see the difference between the two for almost all tasks (except for games... but I don't play often!)
Regarding the screen, 930 has AMOLED! This looks great, but once more... I didn't see "almost" any difference!
The 930 has also the Hey Cortana - but right now I think it is more a concept than a feature that I will use everyday... Moreover Cortana was not available in French at that time (I am French). Now Cortana is in Alpha, but still without Hey Cortana!
Regarding the 830, well it is a really beautiful, light and slim phone! The camera makes great pictures - everytime I am impressed as if it was the first picture I made with my phone! (930 should have a better camera with its 20 mpxl, 4k video... however, I take pictures to post them on Facebook or to save them on the computer... Therefore 10mpxl was more than enough for me, as I don't use Photoshop/Lightroom)
Glance screen is a nice and usefull feature but not a Must have - it is cool to watch the time and notifications during a meeting or... just like that!.
The most important thing for me was actually the possibility to add a MicroSd and the removable battery. While I never bought a new battery for any of my previous phones, I though that it should be usefull to have the possibilty to do it (in case that after 12 months your battery doesn't work anymore...). Regarding the MicroSD - I don't really use more than 32Gb, however I don't want to worry about it (with my previous phones I was everytime looking at it before installing new apps...).
It is all about freedom and customization!
Regarding the battery, I can't say anything about the 930, but my 830 lasts now (almost) 2 days on very INTENSIVE use (WIFI, Bluetooth, GPS always on - 4G network - lot of phone calls, watching shorts video, making a lot of photos, using Cortana for the reminders (3 or 4 a day), reading news... During the first days I got only 1 big day, but since the update (and certainly a little bit less of use

) I am now at 30-40 hours.
Another advantage of the 830 is that you can change the back cover (I bought a flip cover to have a full black) and/or you can buy some -funny- covers just to protect your phone - and it won't be really thick as it should be with the 930...
While this choice depends on you and what you expect from a phone, I would like to recommend you the 830 as I beleive it is the best phone on the market right now (from a price/quality point of view)
(In some way, the best phone would have been a 830 with hardware of 930... just in order to keep the phone during 2 or 3 years without ANY problems! Now the 830 is really good enough, but I am not sure it will be the case in one year with win10 and the new apps...)