Are all LISA savings accounts much of a muchness?

[AmazonGroupie]

I need to open one, but does it matter which bank I go with?

No, some are Cash and some are Stocks&Shares. It can be hard to move provider later (especially once aged 40).

Cash LISA is useful for a first home purchase in a few years time.

S&S LISA is useful for retirement (access at age 60) if a lower rate tax payer - if higher rate tax payer a pension/SIPP usually works out better mathematically.