I like Elijah Thomas. I would never call it "trendy" because of the history behind it, but it's trending massively. Elijah is currently ranked #7 and could easily rise more. Simon is languishing at #254 and has been bouncing around that vicinity for going on 20 years. It's never ranked higher than #198, doesn't look to be rising significantly and is not remotely trendy.

That said, I prefer Elijah Thomas to Simon Thomas just based on flow, and initials ETC are a complete non-issue as far as I'm concerned. However, if you want a name that is traditional and/or biblical and easily recognizable without being trendy, Simon's your name and Simon Thomas sounds just fine.