If nitrogen is better, would filling your tire with neon or argon be more better?....
Not really. There are several factors at work here. The goal is to reduce pressure changes (constant volume assumed) with temperature changes AND to reduce leakage.
Nitrogen leaks just as easily as air, but it effectively eliminates any water vapor content--which is the largest contributor to pressure changes with a conventional air fill. (leakage IN of air constituents is effectively zero due to the pressure difference). While dry air could be used, it's difficult to dry the air sufficiently, and just more cost effective to use nitrogen.
Leakage is driven mainly by molecular size, and nitrogen (or oxygen) are larger than neon or argon, so noble gas fills are bad from that perspective (though SF6 would be great!)
In terms of pressure changes with temperature, since it's non-adiabatic, all the gases are similar, once you have eliminated any condensible parts (water vapor), so that's a wash.
So in terms of ideal gas fillers, we have nitrogen (advantage low cost and dry) and sf6 (higher cost, but very little leakage), so now it comes down to weight (ignoring cost for now). A 235/50-17 tire has an internal volume of about 47 liters. If pressurized to 30psi (gauge), the gas fill (relative to the air around it, so correcting for buoyancy) would weigh ~110g for nitrogen and close to 820g for sf6-- an unsprung weight increase of 1.5 pounds per tire! For larger tires (285/35-19) the difference is even greater, ~120g vs 950gr...and for high sidewall formula tires, even more.
So there is your result, when cost is a factor, nitrogen gives the best performance as it's totally dry and leaks relatively slowly, and if cost is no option, still nitrogen, as it weighs less than the more leak-proof gasses.
The ideal fill would likely be methane, as its molecular size isn't much smaller than nitrogen, it's unreactive with rubber and metals, doesn't condense, and is lighter than nitrogen (saving 50+g of unsprung weight). Of course, it's flammable, and the methane in a tire if it blew out and ignited would be the same as a pound or more of TNT...so that's probable not good.