100% it is more likely to get successful doing video games that doing vlogs. Vlogs are the hardest category to break into. The reason for this is that vlog channels are slightly more sub driven than other categories on YouTube but that slight difference makes a huge difference on how hard it is to get popular. YouTube is pretty much a level playing field between big channels and small channels but when it comes to vlogs, until you have a ton of subs, you're not going to pick up a lot of "free" views that YouTube gives you because YouTube has a harder time relating your content to other videos (which is what gets you in suggested search) than if you're doing videos on a clearly defined topic (e.g. review of NBA Live 2015).
On the pro-side of doing a vlog channel, if you do make it, you can crank out a video every day with minimal editing time needed and you'll get a lot more views from your subs than gaming. For people that are interested in daily vlogging, I recommend that they start a channel about a specific subject - e.g. gaming, cooking, cars, etc. And slowly over time as their sub count goes up transition into more general daily vlogs (think Shaytards).