OK, so let's agree to disagree. Is there any other weapon you're referring to here? Or is the entire basis of saying the cantrip is overpowered is this iffy interpretation of a light crossbow?
If your sticking with 1-handed, then the Javelin, at d6 range 30' + melee.
Which is close enough to balance. Especially since throwing it at low level actually might cost you something.
Otherwise, shortbow is also a simple weapon with over twice the range of poison spray.
If you did something go get martial weapons somehow, then you deserve better than firebolt.
Do Elfs still get longbow proficiency?
Hand crossbow might be best, but again, your investing resources so it's allowed to be better.
Also, they closed any loopholes about crossbow expertise and such. As they only trigger on "attack" action.
Sneak attack is the big one. But since True Strike
must use your spell casting modifier, you're going to be a lower Dex rogue. So you get a little more damage at the cost of AC, and that's fair.
Same with Eldritch Knight. Ironically using True Strike would make it a lower accuracy attack, unless your 20/20, but that's spending feats.