Glenlivet 18 vs 25
 

My boyfriend's birthday is coming up and I would like to get him a nice bottle of single malt scotch (He usually drinks Oban). However, I am a bourbon drinker and know very little about scotch. I was told that Glenlivet 25 is as smooth as it gets, but another friend of mine said that it was too smooth and had no depth to it. He suggested Glenlivet 18 as the most balanced. Does anyone have an opinion of either one? I will also take suggestions for other scotches as well.

If your boyfriend drinks Oban, it would seem he likes at least a bit of smoke. I would recommend Highland Park 18 or 25 before anything by Glenlivet. Dalwhinnie Distiller's Edition also comes to mind, as does Talisker 18. All of these are quite rich and flavorful, but it's a bit of a craps shoot to make recommendations based on one single malt.

Oban is characterized by a light sweet flavor with some light smoke and a bit of a briny finish. Balanced and smooth. If you want to play it safe, Highland Park 18 would be a good alternative. It's light as well with a smooth sweet smoke. Another alternative would be The Balvenie 17yr Peated Cask. It's called peated, but the peat is very mild and comes across as a light smoke with a hint of ash. Nothing like a heavily peated Ardbeg, Laphroaig, etc. It's lovely light and balanced Balvenie, with a little more. I really like it.
If you know some other whisky that he likes or has in has cabinet, we could probably make better recs. The HP is about $100 and the Balvenie is ~$150.

I suppose I should add that he drinks Glenlivet 12/15 also

You probably can't go wrong with the Glenlivet 18, then. Just the same, I don't know anyone who would mind having a bottle of HP 18. You also might see if you can find a limited edition bottle or single barrel bottling of something -- these are difficult to find in some areas (you almost have to go to a serious liquor store: Binny's, Party Source), but make for excellent gifts to a single malt fan, and typically don't break the bank.