The reason I generally go for IC is because its stats key off of Host Rating, which is generally pretty high. A spider's stats are roughly comparable to the decker's (probably a little lower) and device stats (say, Willpower + Firewall rolls) are typically pretty low. If you're bricking guns, you've probably had a few pre-combat rounds to mark things, making your shots essentially auto-kills. If you didn't get the pre-combat prep time, you probably have better things to do than brick guns. While IC can respawn, it doesn't happen instantly. Given how fast a decker moves in hot-sim, this can mean the difference of a few IPs to crack and copy a file.