Put down you more favorable aspects of each edition of
40k, like:
Rogue Trader: (positive) Its the beginning, has some great reading, especially the Ork and Chaos books, but (negative) the rules were all over the place (codexes if you can call them that, White Dwarf articles, etc) and kind of slow going. It didn't start getting good until shortly before 2nd came out.
2ed: Great game box for its time, lots of color and character, its kind of hard finding a negative for me, except for all the cards. But it was pure fun. I still have it.
3rd: Loved the new tactical squad and land speeder, loved how many codexes, sourcebooks, etc they released at this time. Remember that Cadia/Eye of Terror summer campaign (can't remember the name)? Fun. Happy with the army lists in the rulebook, and hate this was the last time this was done. Wasn't crazy about the abstract rules, but it did quicken the game. Kind of makes me think 2ed as Chess, and 3rd as Checkers. I believe this is where the rule forcing models in the units to only fire at the same enemy (even if they either can't see the target the rest are fire at, or don't have other weapons that could be used against it), which I have detested since. The Dark Eldar minis were terrible.
4th: Loved the shuttle terrain, and the Tyranid infestation markers, AND THE FACT THE PUT OUT EXPANDED SCENARIOS in the Battle Rages On supplement (which they would do that for all the game boxes), but wasn't crazy about the units included in the set. I took a break from
40k when this came out.
5th: Never got anything during this time.
6th: Loved the Limited Edition Dark Vengeance set. Loved the Novella. The models
GW is producing now are just amazing, even if I have no interest in playing with/against some of them (like a Wraithlord). Also liked the presentation of the rulebook. It feels kind of gothic. Hate rolling for charge distance and then just standing there if you fail.
7th: Haven't gotten it, and probably never will. I love introductory box sets, especially ones that come with scenarios. But all they did here was re-release 6th with a new rulebook and Aspiring Champion. Total fail to me. I guess I can look for a pocket sized rulebook on eBay...
Looks like I focused a lot on the sets
lol. Well, to be honest I don't collect much beyond the armies included, so that's why I love when they release those sets. Like, for my second edition collection, its based on the marines and orks that came in the set, plus a Captain, Librarian, Chaplin, Warlord, Warboss, and a metal ork dreadnought and buggy. Around 800 Points each I think? I have just about the same in points for the Squats

, Genestealer Cult, Tyrands, Eldar, and Chaos. But with the later editions, I really only went with the forces in the box set with some add-ons.
So what are your pros and cons each?