I enjoyed MGSV: Ground Zero and want to investigate the series further should I buy MGSIV or the HD collection? I have not played either very much and am interested in picking one up. What do you guys think?

screw the hd collection... Get this instead.

Metal Gear Solid: The Legacy Collection

The Legacy Collection includes Metal Gear, Metal Gear 2, Metal Gear Solid 2: HD Edition, Metal Gear Solid 3: HD Edition, Metal Gear Solid 4 Trophy Edition and Metal Gear Solid: Peace Walker HD Edition

I would get the HD Collection because then you get in my opinion the best game in the series which is MGS 3. MGS 3 has quite a variety of environments from narrow buildings to large outdoor sections. It along with Peacewalker should also make more sense of Ground Zeroes' and later Phantom Pain's story.

EDIT: Legacy collection is great too if you can find it for a good price.

You should play all the main ones. Also Peacewalker if you can. Since you started with Ground Zeroes maybe you should play MGS 3 then Peacewalker then 1 > 2 > 4.

Chronology goes like this: MGS3 > Peace Walker > Ground Zeroes > Phantom Pain > The original 2 MG games (You can just read about those) > MGS1 > MGS2 > MGS4.

Peace Walker has the most similar structure, and is the best MGS besides, so I'd recommend that.

They say to not play them like that because the story would be confusing (as if it wasn't already confusing), and you wouldn't know about some characters.

Either get the HD collection or purchase MGS2 through PSN.

It is preferable to play them in order of release to get all the references and stuff, but that's pretty much it. I played them in order of release so maybe it would be more confusing playing them chronologically, but I just don't see how.

I will pass on the Legacy Collection. lol
http://www.amazon.com/Metal-Gear-Solid-Collection-Playstation-3/dp/B00CTKHXFO

HD collection
http://www.amazon.com/Metal-Gear-Solid-Collection-Playstation-3/dp/B0050SX97I/ref=sr_1_sc_1?s=videogames&ie=UTF8&qid=1419010169&sr=1-1-spell&keywords=metal+gear+solid+hd+collectiob

So MGSIV or the HD Collection? It seems most of you think the HD collection?

I am not looking to spend that much money, as I already have quite a few games I have not finished.
Dragon Age, GTAV, FC4, The Evil WIthin, Pier Solar, AC:U (which I dont care for) hopefully all these will hold me until Bloodborne :D

Maybe it is because I have not really played previous MGSs but the story of Ground Zero was all over the place lol