Some amps may be more versatile, some amps may have a particular sound you want or open new opportunities. If you like the sound you are getting and it is loud enough for your current needs, then you don't need a better amp. You might want a better amp, but that is something that never goes away, no matter how much you spend or how fancy your amp is.
If you've never tried an actual tube amp, it's worth checking out. They tend to have a different feel than solid state or digital amps and many prefer the sound of tube amps.
Also, unless you are gigging or playing with a loud drummer, you won't need a high wattage amp. There are some absolutely amazing amps in the 15W-25W range.
But in the end, the best amp is the one you have.