You could probably say Gunsmith Cats is my favorite series as it's what really got me into reading manga in the first place, Berserk is also one of my favorites for sure. :
Gunsmith Cats GSC Bulletproof! ADV Essential Anime DVD Like New 702727006722 | eBay
Gunsmith Cats (1995) 5 FN
Gunsmith Cats — AnimEigo
Gunsmith Cats (1995)
GSC Gunsmith Cats Bulletproof DVD English Subbed/Dubbed Anime ADV AUTHENTIC/OOP | eBay