In my opinion, 4 takes all the good change that 3 created for the series and puts it in a better set of levels and a better story. It's a less interesting setting overall for sure, but the level design is consistent and great.

3 is the change the series needed to stay relevant. I personally think it's a little simple compared to the two later entries of the same style, but it can't be denied that it's the second most important entry in the series behind V2

After the intense "filling a market hole" vibe of resisting Zombie Army Trilogy, i expected very little of Zombie Army 4. That was a mistake. Zombie Army 4 is a fantastic horde shooter. It takes all the good stuff from the earlier Zombie Armys of the enemy variety and general weapon situation, but then just has so much fun with it throwing in boss enemies and special weapons and traps and so much more.

It is baffling that V2 is as good as it is all things considered. Who asked for this game to be made? Who asked for a sequel to the 7/10 Sniper Elite, six years after release?

Alas, it got made, it's an excellent game, and it revived the franchise to its modern success.

5 is by no means bad, but 90% of the time it feels very uninspired. They got a pass with 4 being derivative because 4 has excellent design. 5's design is just kinda worse 4 outside of two or three noteworthy levels (strangely the third mission, Spy Academy, is perhaps the best level in the whole series). Outside of adding an invasion system which is very neat, they didn't really do anything here. It's still a great game, but in no way would I recommend it before 3 or 4

Sniper Elite VR is a little tough to talk about. It came out around the same time as Sniper Elite 5, but is vastly more similar to V2 than the stylings of the games 3 and up.
It's a pretty good execution of that V2 style, but that V2 doesn't really hang as a new release in the 2020s. It's not a bad game, it just feels very fine and overly safe.

The Zombie Army games are a relic of the cottage industry that was Left 4 Dead Clones before we landed on the modern slate of household name co-op shooters.
That is to say, it's a usually not terribly unique or interesting horde shooter that takes very directly from Left 4 Dead. It does do some interesting stuff with enemy types, but in my experience that interesting stuff is sandwiched between a lot of uninteresting "clear the area" style objectives.
It's not bad, but I don't really see why anyone would play it in 2024

It's Sniper Elite VR again, warts and all, but less inspired.

It is astounding that this game managed to spawn a franchise.
Listen maybe this passed for some military mega-nerds in 2005, but dear god its atrocious by any modern standard. The biggest surprise of this whole process of playing every Sniper Elite game is playing this and realizing that some psychopath decided to create the franchise I loved out of it.