MS3 vs. MS4

So if you were in the market to purchase one of the above, which would you choose? If you already own both, which do you prefer and why?

I'd take part 3.
Although I am starting to hate both games now...
Part 3 is much better though.

Thank You,

Jorge

DUCK AND COVER!!

Get 'em both, MS3 first. MS3 has brilliant backgrounds, fantastic music, branching paths, and is all around a masterpiece. MS4 reused many elements from prior Slug games, but still had enough original and different to merit picking up IMO. In particular the MS4 music is very nice, and the gameplay varies enough to be a worthy (albeit not as good as the others) addition to the series.