How do I choose between ionization and photoelectric smoke alarms?
One consideration is where it's going to be installed.

The issue being that some places are more likely to have them go off when they shouldn't.

Ionizing can be affected by steam, so has problems if installed right outside a bathroom.  They also don't work too well if mounted near moving air (forced air systems, ceiling fans, etc.)

Photoelectric are set off by lots of dust, so workshops, laundry rooms (lint) and the like are problem areas for them.

They both have problems in kitchens.

Where you can, you should use combination alarms, but you can also use a mix of types to achieve the same effect, while avoiding areas that might cause them to go off when they shouldn't.