Hard to find a perfect and up-to-date ZX Spectrum emu with full joystick support with remap of buttons -> keyboard keys (e.g. for games with multiple fire buttons), full ULA and ULAplus support, no issues loading all file formats etc.
My best choice ATM is ZXSpin 0.7. A bit old (DX8/DDraw I guess) but still runs fine with almost all features I'm looking for. Hope to see a modern update soon... (I'm already stressing Dunny enough for this
)