Yes, Elena is worthy. If you have elite options then I could see her not being next, but you can definitely feel good queuing her up.
My experience is that she’s better in defense than you seem to think. I find her to be one of the toughest red tanks. Sure, she’s squishy and slow, but if she fires it’s a big problem. And her revive mechanic makes that more likely. I have written about her a few times in my Raid Stats. Here’s the most recent one. As you can see, an 8.47% win rate as the tank is elite. I’ve heard many say she’s easy and that they, ‘never lose to her,’ but I’ve never seen anyone actually present any data backing those claims up. Anecdotally, it’s easy to remember all the times she was no problem and died quickly (and that happens to me plenty, too), but our memories are woefully fallible.
That you have her costume as well just further boosts her. Even if you’re not giving her emblems the costume stats bonus makes her even more powerful.