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... I've already studied up a few possible candidates for subs i'd like to make, but could anyone tell me about the manufacturesrs? which ones are good and which ones are not so good, regarding subs?
Hi Spectre! Welcome aboard!
Regarding the model, it really depends the period and the scale that you want to make your build!
I will list the models (injection only) that I consider easy and good models:
WWII:
1 - Type VII-C 1/72 Revell-Germany .....obvious 

2 - Type IX 1/200 Nichimo (actually they have three versions of the IX)
3 - Type XXI 1/144 Revell-Germany (the closed hull version or the cut-away version, with more work to be done)
4 - I-19 1/200 Nichimo (one of the best models I have seen, from the early 70's )
5 - USS Lionfish 1/220 Revell-Monogram (good hull, but need some work on the flooding holes - the Conning tower could be replaced by an AM resin, but it depends on how much is your "accuracy desease")
Post-War
6 - Russian Kilo 1/144 Trumpeter (easy build, great results)
7 - Chinese Type 33 1/144 Trumpeter (chinese version of the russian Romeo Class conventional sub)
8 - Chinese Type 33G 1/144 (model of few units build by the Chinese with missiles)
9 - Type 206 1/144 Revell-Germany (accurate model of a lesser know conventional sub)
10 - USS Skipjack 1/232(?) Revell (an easy build, with a little work if you don't want to represent the access to the nuclear reactor - part included in the model)
11 - USS Dallas 1/350 DML-Dragon (atention needed in some points to make an accurate model)
12 - USS Los Angeles 1/350 DML-Dragon (almost the same model with replaced parts of the errors made in the previous model)
13 - Kursk 1/350 Zvezda (easy built an to my knowledge, the best kursk in the market)
14 - Oriol 1/350 Zvezda (I can't make any comment, since I don't have this model, but if I remember, I think it's the same as the Kursk model with different decals)
15 - Typhoon 1/350 DML-Dragon and 1/400 Revell (actually none of this models are completely accurate, but for an first build is a great project)
This list is already too long, and there are still more subs in 1/400, 1/700 and probably a few that I had forgotten.  
 
 If you really enjoy a particular sub, go for it!!
The more recent kits are better in details and accuracy.
Appart from some models with a cut-away section, allowing the possibility to show the interior, most subs are easy builds...
Some of the subs that I have listed are now out-of-production. Some of them can be found within reasonable prices "e_you know what" auctions website.
The resin subs are a different story and I would NOT advice a "novice" to start in this media, but if anyone needs help, I'm here and glad to help!!
Hope you're still awake :-) 
Skipper