I have owned both and found the ATMO's performance a little disapointing. It still is quick don't get me wrong but it just hasn't got that kick that a turbo charged car gives you.
If I had to make the decision on both to run as an everyday car then it would be a closer run thing but again would prefer the Turbo.
Resale on an ATMO is harder as well, it took me nearly 3 months to sell mine and only had 1 person to view it

Good luck.
P.S There is a nice looking one on ebay at the moment:
http://cgi.ebay.co.uk/1987-RENAULT-ALPI ... dZViewItem