Is it twice or 4 times bigger than my database? Or, is it ten times bigger?
I use MyISAM because I want a lock per session so that no other session can request while the current session hasn't finished. I prefer MyISAM in some project because of its speed and full text indexing. Otherwise, my first choice will be innoDB.
InnoDB is also good if you want to do transaction where several requests can be handled as one. You can either apply or revert on the InnoDB. InnoDB is capable of row locking and micro locking mechanism.
Innodb is being updated regularly while MyISAM is now almost to being neglected.