Zardnaar
Legend
You asked for a better -damaging- spell at 1st or 2nd level. I worked within those limitations to demonstrate that there are other options that are better. You didn't ask for "What combos best with Chromatic Orb?"
Especially since you can cast Flaming Sphere, smack someone, block a door, and then cast Chromatic Orb or other spells on the following turns.
If Flaming Sphere is maintained for its duration, it is capable of exponentially more damage than Chromatic Orb can do with a 2nd level slot. It also hits more targets, and can do environmental damage, continuously. Is there a tavern or other wooden structure you would prefer not be there, anymore? Flaming Sphere will reduce it to rubble in 10 minutes or less!
You've found your evil wizard BBEG's tower of knowledge? Bye-Bye spellbooks and historical research beyond what you need to take with you, making it impossible for him to ever know what you stole!
Pretty sure there's a goblin hiding in a haystack? MUAHAHAHAHAHAAAAA!
Anyway, yeah. Flaming Sphere can potentially hit many many more targets, damages objects you need it to, blocks doors and spaces, and lasts a relatively long time in D&D Turn Based Combat in smaller environments. (Obviously it's not great for overland travel pre-casting or anything, but still!)
Fkaming spheres good but combats usually over fast (2-3 rounds). Front loading damage tends to be better than over time.