First three things:
1) You are your channel. People subscribe to personalities, not topics. Yes, they find you by topic and will likely subscribe to you based on your channel's topic, but they will only continue to subscribe to your channel because of you.
2) Do what you have passion for. LONG-term passion for. One of the biggest mistakes I've heard successful YouTubers make is starting up a channel because a topic was hot or they had a crazy idea but, in either case, it was only a passing fad for them. Unfortunately, their channel takes off, they start making good money, and now feel stuck doing it. This isn't the same as "be authentic". You can be authentic when you're in the lust stage of a fad. But unless the topic is and HAS BEEN a long time interest of yours, your enthusiasm for the topic will begin to wane and eventually you will even begin to hate being "forced" to do it.
3) Specifically for gaming channels, don't make a gaming channel for a specific game but for a game genre that you love playing. Games come and go. Genres don't. So don't name your channel after a game but for a game genre. Besides, people find you based on the video's title, not your channel's title. So make your channel one that can grow with you. Having said, few gamers like playing all genres. They tend to like only a few genres. Pick ONE genre and make it your focus. Pick the genre that you love the most, have played the most, and has been a long-time interest of yours.
Having said the above three, do the gaming channel AND the vlog channel. Make your gaming channel your primary channel and view your vlog channel as a way to help develop a following for your gaming channel. Only do gaming videos for your gaming channel, throw everything else into your vlog channel, and promote your vlog channel at the end of each of your gaming videos. You hit a milestone for your gaming channel, make a video and post it to your vlog channel. Do a monthly "viewer mail" episode where you answer questions from your gaming channel viewers BUT post it to your vlog channel. If you make a "making of..." video about your gaming channel, post it to your vlog channel. While you need to post at least one gaming video a week (ideally once a day) for a gaming channel, only do a weekly vlog channel. No more. Doing so will reduce down the workload and you'll make better vlog videos by not having to "fill the void" that is a common problem of more frequent vlog channels.
I'm not sure if you'd have enough time to maintain both. but if you're already doing lots of gaming then it doesn't take up more time just to record yourself playing
