I think that I'm finally starting to get bored with this game, but I did spend around 250 hours on it, so I'd say it was a pretty good investment
I'm at ascension 20 with all characters, but haven't beated it yet, though game on a20 is pretty tedious, since you really need some perfect combos to even make it somewhat far in the run.
This also reverses the way you approach the game, normally you just pick good cards and hope some good synergies come along the way - at a20 you really need to take huge risks and hope to get that perfect synergy.
Re advice, I usually play pretty standard/normal builds, the only difference is how I play Defect, I really dislike orb builds (especially frost orb, since it's super slow/boring), so I I often trade of starting relic and usually push either power or 0-cost builds. Claw decks have a really bad reputation, but they can be extremely strong when played right (though they are autoloss vs heart, not so much vs time eater). So, yeah, just wanted to let you know that it's possible to play Defect completely different and have some success
Re fav classes, it used to be Silent, but at higher ascension he is my least favourite - he is so squishy, that you end up with essentially same deck everytime, because if you deviate from taking un-situational best cards, you will just get crushed. For example, cloak and dagger is simply a pick evey single time it is offered, other classes don't have so many common must-picks.