If you don't need the Layer 3 features then stick to Layer 2.
One advantage to converting to L3 from the get go is that you won't have to wipe the configuration if you decide you want the features in future.
If it were me, I would go L3 as the switch will work fine as a L2 switch, even in L3 mode. If you decide 6 months down the line that you want L3 features then its factory reset time. At least being in L3 mode from day 1 means you can use the features in future if needed.