any plain old text file would do. still there are two things you should watch out for:
don't forget to use your file in open/write/close sequence. people often tend to forget about the "closing" part, they open a file and keep writing until something happens (crash, reboot?) leaving incomplete file. if you use python, this should take care of it:
with open( 'log.txt', 'a' ) as log :
print >>log, date_time, temperature, humidity, latitude, longitude, etc...
"with" will automatically close the file, so you don't have to worry about all this "you must restart after rotating the log" nonsense.
also, you don't really need to store temperature and humidity every 10 seconds, unless in a very harsh environment. it might be a good idea to write three separate log files and store the values only when changed -- this might considerably reduce your file size and wear of your SD card.