Lebesgue: I couldn't disagree more with what Endurium wrote.
It is not true that when you play BG:EE you will have the same experience as the original for two reasons:
1. All original cutscenes were removed in BG:EE.
I would disagree this is an issue. Old FMVs were in a very low resolution. The new ones have a different style, but it still looks quite fine IMO. If you want to experience the game as it was made, it can be a problem. But it's not the purpose of a remaster to leave everything like it was in the original. The meaning of cinematics is the same. There were no plot changes.
Lebesgue: 2. You cannot avoid new companions. You can choose to dismiss them, but you will be forced to interact with them at least a little bit.
I view the new companions mostly as a good addition to the game. I have doubts only in the case of Baeloth which is too grotesque for my liking. The interaction you're talking about is only brief and there's nothing that spoils the game when you come across them. Even if you don't like the new companions, the advantages of EE are enough to justify buying it.
Lebesgue: 3. Interface is changed and for the worse. The last time I played, the journal was a mess.
If you're used to the classic interface, you may feel a little weird when interacting with the refreshed version. It has some serious pros however. There's no need to endlessly scroll the descriptions on the character screen as Beamdog implemented categories. In the original you could see only a very limited amount of items on screen when buying and selling. This is resolved. I can't imagine how someone can prefer the original journal. This is were we came across a true mess. These days the quest entries need to be clearly accessible without the need of endless page turning. It's good that EE introduced a separation between quest and other entries. On the inventory screen we also have some nice changes. There's more useful information which makes gear management easier.
Lebesgue: I understand that the main issue is the low resolution of the original. There is a widescreen mod for the original that fixes that though. So if I were you, I would start with the classic edition. Only if you think the classic edition is unplayable due to graphics (which to me are fine) I would suggest switching to BG:EE.
The problem with widescreen mod is that it makes all of the assets tiny, if you're playing on higher resolutions. In 1080p the game is almost unplayable for me, especially when a lot of things are happening in a very limited space. EE solves this problem by introducing zoom. So if you don't use a monitor that has a native resolution lower than 1080p, EE is the way to go. :)