@jSz28, neither of those two is ideal for you right now, and I wouldn’t be particularly excited about giving sturdy shields to either of them, although either is better than a 3* hero.
If you already have four compasses and four gloves (or more), that means you can ascend Falcon, Jackal, Sabina, AND one green hero. (When you get the hidden blades, orbs, trap tools, and sturdy shields)
All three of those mentioned are more widely usable than Kashhrek.
There are exceptions, but most 5* heroes at level 3/70, are far weaker than most 4* heroes at 4/70, and they take the same ascension items (had to get), and take MORE feeder heroes and MORE food to level them up. And then you need the materials for their final ascension which are much harder to get, and they are hugely expensive to level up as well.
Note: Elkanen isn’t one of those rare exceptions…
You are far better off maxing out two sets of 4* heroes (2 of each color), maybe three sets before you seriously work on any 5* heroes you’ve been lucky enough to get. By that time, you will have more of what it takes to level them up and utilize them properly.
My recommendation for you is run one TC at 13, one TC at 11, and keep those queues full. You can move recruits/heroes between the two as a way to store excess food / retrieve stored food, since there is a lot more food stored with each recruit in TC13 than TC11. I’d do this until you can run TC20 instead of TC13.
Your third TC, I’d work on upgrading it to catch up with your stronghold as you can … and between upgrades, run either swords or backpacks through it, or run it at TC11 (or TC4 until it is high enough level.)
Upgrading your stronghold and one TC to 20 as fast as you can is the best way to get 4* and 5* heroes without paying for summons.