Unsure which arduino to buy

I'm doing a project where I will be making a robot to play a tin whistle.

I'll be using 7 solenoids and possibly a variable flow valve for air. I'll need to program the arduino to play the music. Which model do you think would be best suited?

Thanks

An ATTiny85 with some SN74HC595N could do this…

But for simplicity sake, an UNO is a good place to start.

Not a 74HC595, not enough drive current. TPIC6C595 (100mA per output), TPIC6B595 (150mA), or TPIC6A505 (350mA) would likely be better choices for solenoids and a flow valve.

Attiny not much memory either (8K). Uno (32K), 1284P board (128K), or Mega (256K) likely a better choice.

CrossRoads: Not a 74HC595, not enough drive current. TPIC6C595 (100mA per output), TPIC6B595 (150mA), or TPIC6A505 (350mA) would likely be better choices for solenoids and a flow valve.

Attiny not much memory either (8K). Uno (32K), 1284P board (128K), or Mega (256K) likely a better choice.

An important fact is that the 1284P has twice the SRAM of the 2560 (16K vs 8K).

I've actually been growing to like the 1284P more than the 2560. I have not yet ever needed 256K of flash, but having lots of RAM has helped me several times.

For the development, a Mega would be a good choice if you want to stick to a native Arduino (1284 based boards ain't as far as I know). Once your setup and code are complete, you know how many pins you need and how much memory. You might find that it all fits on/in e.g. an Uno and use that for the final implementation.