Hi Uriel222,
I actually just went through this process assessing Roll20 and FG a little bit ago. I ended up choosing Fantasy Grounds and have been pretty happy with it. Here's the thread that I started back then that has some decent information:
http://www.enworld.org/forum/showthread.php?514874-Roll20-vs-Fantasy-Grounds.
Here's a decent overview of the two that's in that thread also (although Roll20 does now have access to some of the WoTC stuff, FG has it all for 5E):
On pricing; many comments on prices are misleading. If you want a perpetual license (which I recommend) it is normally $40 , and rather than each person getting a license, only the GM needs an ultimate license, $150, which lets you have as many free/demo licenses as you want. But, you can't hand off the DM roll if you do this. So, you probably don't ever need to spend $200 on just the s/w, though it is possible to have a use case for such. Prices for modules and add on are the same price as if you bought the hard/print versions. So I don't see that be any type of additional cost. i.e. no matter what format or VTT you use, the cost for a module or an add-on like Volo's Guide to Monsters is the same. Plus, I find the FG version so much more capable as a reference source (links, drag and drop, etc).
Now, Roll 20 also is licensed, and has been for some months, but they only have a small set of the WotC content available for purchase. Though that's always changing, and maybe they are releasing more of it now, but last I checked they only had 3 of the products. Also, Roll 20 really isn't free. Not if you want anything close to comparable functions.
There is a comparison chart that is ok if you understand the nuances. Third party chart here:
http://battlegroundsgames.com/vtt-comparison-chart/
FG's comparison chart here:
http://www.fantasygrounds.com/forums...VTT-Comparison
So, there were 3 reasons I chose FG over all the others when I started in about 18 months ago:
1) The FG community. It's incredibly (by far) the most active and pleasant community on the web I've ever been a part of. I've heard talk from others that the Roll20 community is either great, or if you express a dissenting opinion or mention a competitor your post will be deleted and eventually you will be banned. Don't know if that's true, but have heard it from at least 3 people who say they were banned for things like asking about competitors or complaining about support. Also, FG support is great, and they basically have a money back guarantee. See;
http://www.fantasygrounds.com/forums...back-guarantee
2) Official WotC content. At the time, they were the only ones who had it.
3) Architecture. Roll20 is SaaS. FG is local client. If either company goes out of business, what happens to all your data? With FG, It's all on my computer. And with the exception of a license check when a free player tries to connect to an ultimate license, you don't need internet connectivity. With Roll20, you lose it all. Something like this already happened a month or two ago with Roll20. Their jukebox function was done through an API with Syrinscape (?) and Syrinscape pulled the plug on them. If the R20 admins knew it was coming, the users never did. They have since replaced it somehow, but I'm not sure how it compares and what people with sound libraries had to do and if they could even recover their sounds.
Automation and s/w capabilities. Though FG does not have dynamic line of sight (which is a paid function on Roll20), it has a great deal of things that make it really easy to play and to create campaigns. Though I admit the UI has lots of idiosyncrasies, it is very powerful, and I didn't find it too hard to get used to or to learn.
A few technical things; FG has a very active set of user developers (since it's almost all open, written in XML and LUA). Linked sounds (which is basically the same as R20's jukebox) are a function done by a community extension (he actually works contract for FG on occasion, so you know he's trusted) Fog of war is included, but it's a basic masking and unmasking of the images. Their have been technology demos both from FG and the community on a dynamic line of sight, but its not expected in this version of FG. FG has a Unity version that has been in development for a few years. Though the company makes no promises when, and says buy the s/w for what it is now, the FG Unity version is expected sometime in 2017.
Connectivity can be a hassle in a few cases. This is because of the local host architecture and the use of IPv4 protocols. Worse case it requires the use of a vpn (Hamachi or private vpn server, which costs about $15/yr and one of the community developers has a document with step-by-step instruction on how to set one up).
I hope this helps and that you pick the right decision for you and your group. I've been loving FG and am very happy with the decision (as is my group). Good luck in your decision!