Is this a good reroll?

Hercules one of best servants, so I think it's good start for you.

That's a good roll. I'd keep it if I were you. Herc is an amazing ST berserker, and has amazing survivability if you invest in him. Euryale and David are really good when used appropriately. Also, don't waste your quartz. If you're free-to-play, save all your quartz until you get a rate up for a servant that you really need/want. Save all your golden tickets as well.

It's early for you so it's better to adopt this expectation early on:

3 quartz is not going to get you jack shit.

Lower your expectation to the point where you'd be completely unbothered when you drop 200 quartz and didn't get a single 5*.

Good roll btw.

I think you have some excellent servants there.

I didn't know about rerolling back then, so I started my game with only Elizabeth and Boudica. >_>

I started with martha. You'll be fine.