Metal Slug: The best ones and your favourites

Recently I have gotten back into the Metal Slug games. Initially, this has been via the Metal Slug Anthology on PSP so I've been playing through 'slugs 1-6 (and X) to remind myself of each game and which ones are the ones worth spending time on trying to improve.

Unfortunately this hasn't included Metal Slug Advance (great game but I no longer have my copy and haven't gotten round to emulating...yet) or Metal Slug 7 and it's XX enhancement.

But I would have to say that the three "proper" games by Nazca - MS1-3 - are the absolute best without a doubt. The rest are hit-and-miss since other people made them and not really essential in my eyes (even though some are still worth playing).

Metal Slug 2 - Personally, I find this the most balanced and replayable. Builds on the original and is still hard but also so fun.

Metal Slug - the original is probably the most pure game and very close to MS2 for me. I personally prefer the lack of aliens and supernatural stuff in this.

Metal Slug 3 - Clearly the absolute peak of Nazca's creativity and artistic endeavour with the series. You can see how much love oozes from every pixel. Branching routes adds extra replayability. Some people say that MS3 is THE best, but I can't bring myself to agree purely based on how stupidly long and sadistic the final stage is. It's amazing but exhausting and so, so brutal.

Metal Slug X - essentially a remixed version of MS2. The only reason I put it so low on my personal table is that I prefer vanilla MS2 as X actually feels harder (the tomb stage has new enemies and is tougher for example). On the plus side, it fixes the slowdown that plagues MS2 in certain sections, and introduces the mighty Enemy Chaser.

Metal Slug 5 - Big improvement on the shoddy hack job that was MS4 (see further below). One of the fairest 'slugs imo and one hell of an epic final boss. Also features a sliding move which is fantastic and allows you to cover short distances quickly and slide beneath bullets, bombs etc. You can also shoot while sliding! Tragically, the slide move was removed from MS6.

Metal Slug 6 - First non-Neo Geo Metal Slug (Atomiswave) and very different. You can now use Ralf and Clark from Ikari Warriors, and all characters have their own individual stats, skills, and a special attack. You can also stock two power-ups and save them/switch them. Loses points for simply not having the charm of the Nazca games and the final levels just being absolutely nasty with aliens and other weird creatures, and much cheapness with screens full of crap and bullet sponge enemies that suck away your credits. That aside, I do actually like the new additions to the gameplay.

Metal Slug 4 - the first non-Nazca game and easily the worst in my opinion. There is little charm, the music is forgettable, and there is a constant and blatant re-use of assets from MS1-3 - usually re-skinned or re-coloured enemies and bits of old bosses added onto new ones. The re-used Nazca sprites really clash against anything new and lower in quality that was drawn specifically for this game. Still a solid run 'n gunner, and it features 2 playable characters never seen again, but I would never choose to play this again over the others.

Anybody else a big fan and what are YOUR favourite Metal Slug games or moments in the series?