whose game should I learn if I want to be a positional player?

Magnus

Capablanca first comes to mind. Difficult to beat and with a legendary reputation with the endgame.

Some possibilities for reading:
50 Essential Chess Lessons by Steve Giddins
https://web.archive.org/web/20140708100833/http://www.chesscafe.com/text/review534.pdf
Simple Chess by Michael Stean
https://web.archive.org/web/20140708104258/http://www.chesscafe.com/text/review400.pdf
Amateur's Mind by Jeremy Silman
https://web.archive.org/web/20140708094419/http://www.chesscafe.com/text/ammind.pdf
Chess Secrets: The Giants of Chess Strategy by Neil McDonald
https://web.archive.org/web/20140708092313/http://www.chesscafe.com/text/review620.pdf
Chess Strategy for Club Players by Herman Grooten
https://web.archive.org/web/20140708101926/http://www.chesscafe.com/text/review696.pdf
Chess Training for Post-beginners by Yaroslav Srokovski
https://web.archive.org/web/20140712013538/http://www.chesscafe.com/text/review945.pdf
Chess Strategy: Move by Move by Adam Hunt
https://web.archive.org/web/20140708093249/http://www.chesscafe.com/text/review890.pdf
How to Reassess Your Chess (4th ed.) by Jeremy Silman

https://web.archive.org/web/20140708095832/http://www.chesscafe.com/text/review769.pdf
Winning Pawn Structures by GM Alexander Baburin (1998)
https://web.archive.org/web/20140718055446/http://chesscafe.com/text/wps.txt
Understanding Pawn Play in Chess by GM Drazen Marovic (2000)
https://web.archive.org/web/20140708110136/http://www.chesscafe.com/text/review249.pdf
Dynamic Pawn Play in Chess by GM Drazen Marovic (2001)
http://theweekinchess.com/john-watson-reviews/books-of-many-flavours
Winning Chess Middlegames, An Essential Guide to Pawn Structures by GM Ivan Sokolov (2009)
https://web.archive.org/web/20140708091955/http://www.chesscafe.com/text/review676.pdf
Pawn Structure Chess by GM Andrew Soltis (2013)
https://web.archive.org/web/20140708101523/http://www.chesscafe.com/text/review908.pdf
Chess Structures - A Grandmaster Guide by GM Mauricio Flores Rios (2015)
"There is also masses of stuff in the book that made me go 'Oooh!' and 'Aaah!' so I think it will have the same effect on you! In particular, I loved Rios' exposition of White's plan of exerting queenside pressure against Hedgehog systems. I'd seen one of the games he quotes in his chapter but I'd never remotely made any link to a structured way of fighting the Hedgehog structure, so this chapter was a real eye-opener for me ...
In conclusion, warmly recommended. Lots to learn!" - GM Matthew Sadler
The Power of Pawns by GM Jörg Hickl (2016)
"The didactic concept of the book is admirable. Each chapter defines the structures, explains the typical characteristics and shows the plans for both White and Black. The reader participates by assessing positions and invariably receives useful tips for practical play." - FM Harry Schaack

Zurich 1953 by Bronstein

http://exeterchessclub.org.uk/content/review-zurich-1953-bronstein

Python Strategy by Tigran Petrosian
http://sagarteacheschess.blogspot.com/2015/09/python-strategy-book-review.html
Petrosian’s Legacy by Tigran Petrosian (1990)
https://web.archive.org/web/20140708103409/http://www.chesscafe.com/text/review309.pdf
Petrosian: Move by Move by Thomas Engqvist
"Engqvist gives us a rare treat and a genuine, sympathetic understanding of one of chess' greats who nowadays tends to gets lost in the shuffle!" - Michael Ciamarra (2014)
Grandmaster Chess Strategy by Jürgen Kaufeld & Guido Kern
https://web.archive.org/web/20140708093410/http://www.chesscafe.com/text/review812.pdf

I would look at the games from Tigran Petrosian, Anatoly Karpov and maybe also Magnus Carlsen. Python Strategy was mentioned in the last post which should be a decent recommendation for a book. hope this was helpful

Nice topic OP.

I urge you against learning either Capablanca or Magnus because they are psychics with a psychological style. However, the games of Botvinnik and Karpov both come to mind. 

Neither one nor the other. You are what you are in chess and your behaviour on it hardly can be changed. If you like to play solid, then play solid openings and defences like the Queen's pawn, English or Reti Opening. If you play with blacks, the Nimzoindian, the French, the Sicilian or maybe the Caro-Kann: play, experience, and take the harmony in all your games, according your style, and you will little by little sucess.