I find it fun to always try and balance my team, thus I prefer to choose a class and build something around it. My go to build is 1:Witch with Rouge/Areothurge/Hydro 2:Warrior with War/Terra/Hydro 3:Wayfarer with Ranger/Terra/Hydro and 4:Wizard with Necro/Pyro/Summoning because it allows me to setup a myriad of devastating solutions , but the fact that my team also usually has a Custom Lizard,Red Prince,Beast,Fane comp makes me question other factors.
All in all, it's hard to truly mix melee and magic though not impossible if you put in the effort.