Here's my take:
SR1 The original gangster. I have the core book but I've never actually played it.
SR2The one that started it for me, fond memories of my youth. Due to inexperience of my youth (I had only played AD&D 2nd prior to this) I didn't find anything wrong with the system.
SR3Like SR2 but better. It was super easy to min/max and break the game though... I've had to deal with a few players with " GM Tools
TM " (i.e. you wake up naked, all your gear is gone) lol
SR4My group played this version a lot, it simplified and streamlined stuff so the mechanics went a lot faster and smoother. I don't like how deckers basically ceased to exist in the traditional sense, replaced with on-the-fly hacking. My group was never into decking though as in previous versions taking time out of a game so a decker could do their thing ended up boring everyone else. This hacking model made it so you could use that mechanic during combat to do interesting things.
Examples:
- Hacking someone's cyber eyes to blind them by turning them off
- Hacking someone's cyber eyes to adjust the video feed so they'd shoot their friend instead of one of the player characters
- Hacking a smartgun link to eject a magazine
- Hacking a commlink to turn on Augmented Reality overlay so in combat their vision would be obstructed by all the advertisements floating in AR (effectively giving the player character cover bonuses)
Hacking was fun, but didn't feel true to Shadowrun, not that my group cared that much.
SR5I've got a virtual copy of the core book and I've read through it but I've never actually played it. It seems to streamline the game system even more than SR4 to make it faster, brought back decking, but feels like it was missing some of the gritty-ness of SR somehow.
SR6I've only read bad things
SummaryIf I were to summarize (and also point out it's been like 10 years since I've played a game of SR), I think SR4 ended up being my favorite. I felt like the gritty SR-ness with the mechanics flow balanced well for overall fun. Since my gaming group at the time had no love for decking the hacking model actually added to the game for them.