Best Non-Event Bots

Hi, I was wondering what were the best non-event bots to upgrade.  I have up to Dark Megatron + Rodimus (which is an event bot), and I know EGL is good.  I also know that when Dead End comes around in the next event, he's something to earn.  All of my bots are at least level 7, so which regular one should I upgrade?My EGL is currently upgrading to level 11 and has a 75% promotion.