Features wise,... 6260 is more complete compared to 7610 and thus may have the edge over 7610.... It has EDGE as well while 7610 doesn't....If ur looking for quality pics though,.... definitely the 7610 is better (1 Megapixel),... and if u want the best cam pics, forget bout both these phones and get the 6630.... but since it isn't in ur option,.... i shan't go into that,....
As Ripper3 had said,... 7610 looks better but that's just my opinion,... u may or may not like 6260's design... Personally, the 6260 i feel doesn't look nice despite it's rotating screen,.... feel they (Nokia) had done a better job with 7200's design....
Verdict - For features, 6260
Fashion, up to u but 7610 looks better,...
PS: I tried my best not to be bias cuz i have a 7610....