I say both so long as your computer can handle streaming. You might have to do it on a game by game basis though, depending on how resource hogging the game is and on whether you intend to play PC games or not. A good example of one that would probably be better for just Youtube would be Left 4 Dead 2 (at least from what I remember) because it is a massive resource hog.
I wanted to stream at some point too, and my idea was to stream the games, and then add in some additional edits and post commentary to the footage before uploading to Youtube. Good luck no matter what happens though. ^_^
I'd say gaming stream, cause then it'd be fun to watch you as you play and see your reactions and what not at the moment instead of in a video that not too many people are going to see cause Youtube is Youtube like that .3. (Yes this is the best explanation I have, it's crap I know xD )
I prefer livestreaming because we get to see the personality side of you. We can chat as we go through live playing a game, even offer you tips and tricks (unless no backseating of course). Live streams also let you instantly play with other people and your friends and listen to their funny quirks and commentary.
I know that one of the backdrops of this is that if you're doing this live, you are going to make some mistakes. It takes a while to stream a perfect video and such (even if my internet is not good) and that your commentary will be not perfect... and a bit aggressive at some parts too. Keep in mind that you may get hooked on livestreaming. When I started watching livestreams I got hooked enough that I would watch more livestreams than watch Youtube. One good thing about streaming is that you can have past broadcasts and you can put those past broadcasts into Youtube so it's kind of a win win to me. Anyways it's you who decides this decision on what to choose. Good luck c:
It would depend on the game or the format. If it's a short game (like FNAF), youtube and/or stream it. If it's a somewhat long or medium length game, a stream would be great (if you plan on only doing a segment or everything in one sitting) so long as you can interact with the audience, or otherwise make it a video series with segments. It really depends on the game and how much of it you plan to make into a video/stream.