Just wanted to know what’s the best Bluetooth aftermarket head unit for this car

I have an Alpine 6 cd head unit

 

Define, best. For the money, the best for me was a JVC Double-DIN, KW-R935BTS. This is not a paid commercial for Crutchfield, but they do a nice job with their website guiding you to equipment that you are interested in, there tech support is fantastic and there installation prep service can make head unit replacement a plug-n-play if you are willing to pay up for the extra service. .02

 

I tend to like kenwood stuff. They seem to use the same harness across most (if not all) their head units, so if you ever change to a newer unit it ends up being just plug-and-play.