I currently have a 14.2, a 14.6, and a 15. All set up for the random shit I skate at FDR.
If you want to charge into things like curbs, coping, and pool coping, the longer ones are great.
For ledges and street, that 14.2 is perfect.
It's hard for me to only skate one thing. So I just mess around with shapes and wheelbases. It can be frustrating but it totally matters.
I went almost 20 years with old heads telling it didn't matter and that it was all on me to make the board work.
I would also try to figure out whether you like hi or lo trucks and take it from there.
Otherwise, fuck that boomer ass logic about "You just don't want it enough" or "you're not trying hard enough".
Figure out what you like and go from there. This shit can be too expensive for you to hate what you have.
If the board company doesn't provide that info, maybe they suck.