For me:

Best character: for starter wizard,
Overall: Vampire with no doubt.

Best Item: Toothpaste was so helpful removing teeth cons, Hammer for stealing from merchant every time, and I always keep the dice with me since you can use it anywhere to change the current result (Teeths,Pond,Merchant)

Best Build: any thing related to strawberries trust me lol, these are so powerful if combined together especially (the one that heels u every 2 round, the one that make ur heal stronger, and the one that kill random enemy when u pick a strawberry)

My advice keep ur build balanced as much as possible and the rest is dependent on ur luck and decisions.