Most Helpful Training Method

(other than tactics training), what do most consider the most helpful training method of the following for an under 1500 player:  

a.  Going over master games, covering the moves and guessing what move was made, seeking to build chess intuition, such as CJS Purdy recommends

b.  Playing against a computer, slower games, step at a time, recording the games and then going over the losses carefully 

c.  Study Book of going through principles, with analysis, etc (My System, How to Reassess)

d.  A book dedicated to explaining games, move by move

Thanks to the Experts to Masters who weigh in!

Not an expert/master but have been where you are at (sub-1500) and here's what I would pick in your list In order of preference (most efficent to least efficient)

a. , d.  c,  b.

A few notes:

1. You missed the most important one => getting your games critiqued by stronger players and trying REALLY HARD to not repeat the same types of mistakes from game to game.

2. Playing vs. a Computer  makes more sense when you are practicing technique (holding a draw, winning a won game, endgame) and is quite inefficient when you are training to actually beat humans.

3. Enforcing a "reinforcement loop" in your study process when going over your own games.  For example.

a) Record a mistake (strategic/tactical) I made in a game.

b) Find out why I made it.

c) Review it again the next day => test yourself to see if I make this mistake again?

d) Review it 3-4 weeks later and see if this mistake has "burned" into your head so that you'll NEVER EVER repeat it.

Rinse and repeat steps a) - d) for every mistake you make.

Thanks for your reply....and for understanding where I am it.  

Work conspires with family and geography to preclude your excellent suggestion by seeking out stronger players to go over my games (though I could do it via internet).  I skipped tactics because I am going through tactic books and have reached more than 7,000 on the Tactics Trainer website.  I am attempting to map out a strategy for improvement. 

I love reading and have Dan Heisman's excellent book and have gotten my library set for the coming winter.  I am now trying to prioritize my studies, knowing that I may not have opportunity (or time) to play live, OTB in person chess.  

Not 'b' : you must play against human players.

Other 3 are useful, maybe 'a' a little more, provided you pick old annotated games (before 1970 is a good cut-off) over modern ones. 

'd' could be used for 'a' training : you look for the moves first, then read the annotations and explanations.

I found playing against computer useful in following cases:

1. Endgame training. For example I have all the positions from Dvoretsky Endgame Manual in a file and each position is commented with expected result (white to win, black to draw etc.). So I play against computer trying to win or draw. Quite often computer plays moves that are not analyzed in a book and you have to find the right reply.

2. Tactical training. Again I have a file with positions. The idea is not to stop after you find the tactical trick and win the material. Play on until you are sure that you are going to win.

3. There are books with non-tactical exercises like "find the right plan". Playing those positions against computer is a way to check if you can handle strategy and tactics at same time.

4. Master game – pick a critical position from the game you are studying and play it against the computer.