for nastolgic reasons (my first, and second) i would recomend the 1000. having a detached keyboard can be a really good thing.
also many if not all of the expansions that plug into the cpu socket for a 500 and 2000 will work for the 1000
these include accelerators (14mhz 68000, 68020, and even a 68030 irrc) also adeide and adscsi allow ide and scsi expansions too.
with my amiga 1000s the color composite was great, it is clear and then you dont have the 520 hanging off the back of the 500.
cpu socket stuff might need a socket extender and rom switchers might need some othe hacking to work so you can use roms