I like to start my arenas 4v5 and ToW cant do that for me xD
I'm really torn on this issue.. due to the big killing capacity you gain from TOWs, I can basically start my games 4v5 aswell, but not always.
From there on, when it's 5v4, and I have TOWs, I'm in a MUCH better position than 5v4 with NS on cooldown.

Then there's the nova/etc totems to consider.. can't really make up my mind.. I've respeced back and forth about 5-6 times the last month.