Which Growlithe is better to evolve?

Not much in it, but I'd probably go for the higher IVs. The Growlithe's current move set has no impact on the evolved one.

It took me four attempts to get an Arcanine without bite/bulldoze...

If you want a higher CP and defend the gym, the 616 one. If you want to hold much longer and attack the gyms, 618.

If you evolve both and get the same moveset I doubt you would be able to tell the difference. Go with the one with the better moveset for what your looking to use it for.