New Head Unit Advice Please

I have a JVC KD-SH99R Head Unit, which I've had for about 2 years. There's
nothing wrong with, but me being me, I'm getting a bit tired of it and want
a new replacement.

Whatever I get, it will have to be able to play MP3 discs (preferably CDR
and CD/RW) and have pre-out's for a subwoofer, as I have an Active Sub.

I don't know all that much about stereos, but from what I've seen Alpine
seem to be about the best, so what should I go for. Will there really be
that much difference between my current JVC HU (50W) and a new Alpine model
which seem to be 60W?

Or an I just better off sticking to what I've got??

Thanks. This is what I have incase it makes a difference:

JVC KD-SH99R Head Unit
Infinity REF6953I 6x9 100W RMS
Infinity BasslinkX Active Sub