Hi Anant,
The Maxell XL II 90 is a decent cassette. Even better is XL II S 90. Both are chrome cassettes.
Similar cassettes in the TDK line are respectively SA 90 and SA-X 90.
I have all these (in plenty) and all of them are in working condition. Even normal cassettes (Sony) bought in early 80's (81/82) are of such high quality that they seldom have given me any problem till date.
If these cassettes are in their original plastic packaging, they would be air-tight I'd guess and therefore would be free from fungus.
Regards.