Let's start from the obvious, we all want the SL100R but not many will have it.

The 1200 MK2 is an iconic deck (IMO) and I like the stock look, I got a NOS one and I won't change it. I will rewire and check or even upgrade the arm's bearings but I won't change anything else. I view it this way because it's not my only deck, I like having more than one decks so I can afford to do that. I also think it gets harder with time to find either NOS or only home used MK2's so one should think about it before modding it to the point it does not remind the stock deck anymore. There are people who love doing the mods and seeing how the sound is improving step by step, if you are into it it's the way to go. Personally if I had to choose between extensive mods and the 1200G I would go for the 1200G. Also, the SP25 and the SP10 MK2 can still be found for sensible amount of money. Yes, the less expensive ones don't come with an arm or plinth but I would prefer building a deck to my specs based on those two than the 1200 MK2.