G500/600
I agree with Jaba. Plus, you can't buy a G1000 and retrofit it to your older aircraft, they are only available with new aircraft from the manufacturer.
The G500/600 are whats available for retrofit.
I have a G500 and GTN650 fitted to my PA34 and it has run with no issues what so ever going on 14 months now. I also had the backups changed over for solid state electronic devices, so there is no vacuum system (not even the pumps) at all on mine, which is brilliant. Mate of mine operates a PA31 and has had 2 vac pumps (same side both times) break in that time.
Change over to them, you won't regret it, from a reliability point of view, and actually flying it. I find for me, I can fly longer with less fatigue than I can on steam driven analogue.