Like the OP, I have tried very hard to like Firebrand, but I hate the tome mechanics, and it feels dirty to me knowing that it's so OP because it's the favorite class of dishonest devs.

I have generally enjoyed playing core and Dragonhunter GS builds, so that's what I roll with. My current mathed-out gear set is Dragon weapons, Valkyrie armor, and Marauder trinkets. With that setup and a tier 10 jade bot core, I have over 21K HP, over 2800 Power, 98% crit chance self-buffed, and 230.8% crit damage, before adding extras like food and utility. Massive burst damage and I can take a hit or two when I need to instead of being instantly downed by a breeze. Hope that helps.