IwubCheeze: For me, it's a matter of principle. Do you support GoG's policy or do you support Steam's?

Warning: Incoming semi rant

For me, its GoG hands down but this is a biased comment because my first and only experience with Steam was when I got Half Life 2 shortly after release. At that time, Steam was about as user friendly as a junk yard dog. After installing Half Life 2, instead of being able to play the game, I had to sit through mandatory updates which really soured the experience. I thought Amazon sent me a faulty CD so I sent it back requesting another only to find out it was a "feature" in the installation. At that time, I only had access to a dial up connection to download several hundred megabytes. I ended up leaving the PC on overnight and hoped to hell the connection wouldn't get interrupted and that was just the updates for steam. After the Steam updates were installed, I now had to update Half Life 2 and leave the computer on again for a second night. Tried running the game without updating but Steam wouldn't have any of that. After getting everything updated, still couldn't start the game because I had to be online which was also a pain. Apparently you could turn it off, sometimes it worked, sometimes it didn't. I found my internet speed was worse too because Steam was always sending packets of data home. I checked the option for steam to stop that to save bandwidth but Steam was still transferring data. In the end, I tried to finish Half Life 2 as quickly as I could to get Steam off my computer.

I don't care if I haven't used a dial up connection for a while, I don't care if the most updated games give the best experience (potentially making my saved incompatible), I don't care about online achievements and I don't care about features I'll never use. If I can't use the software I bought without you telling me how and when I can use it, then you should be paying me to use your service.

After finishing half life 2, I uninstalled it, uninstalled steam and got a pirated version of half life 2 instead. I'm sure Steam has changed a lot in the last 10 years so I don't know what it's like now but I just can't be bothered trying it again after such as intrusive experience.

Rant off

Edit: @OP, another thing you might want to consider is if you want to mod your copies of Deus Ex. I don't know how mod friendly Steam games are but logically, with mandatory updates, it seems likely game files could be corrupted. Keep in mind I've never tried this so it might be better to ask on the Steam forums how mod friendly Steam games are. The Fallout games and System Shock 2 I can't imagine playing without mods so for me, the assurance that I can safely mod my copy of Deus Ex without Steam wreaking my games with updates are a plus. Not sure if this scenario is likely as I don't have the experience but if you want to mod Deus Ex, I would ask on the Steam forums how safe your game would be.