Hi. Ever tried juice cabin? If you've heard of Vape it With Les you'll know. He has some great custard flavours in different nicotine strengths. For good throat hit, try his Bloob juice. I'm currently vaping on Key Lime Cookie Dough from U.K. LABS, and Neon red slushie from Far (element).
Unfortunately I know very little about the iSub G leaking issues since I've never owned one. Last two tanks I've had were the tfv4 and tfv8, with both, I've never experienced leaking issues that were not my own fault, I.e. over-priming my coils, or not screwing them in tightly enough. Check your o-rings, they do wear over time. Not hard to replace, just a small tool like a mini flat head screwy can help to remove the old one.