Well, you decide
GRUB has a more powerful, interactive command line interface. LILO, on the other hand, only allows one command with arguments.
LILO stores information about the location of the kernel or other operating system on the Master Boot Record (MBR). Every time a new operating system or kernel is added to the system, the Stage 1 LILO bootloader has to be manually overwritten, otherwise there is no way to boot the new OS or kernel. This method is more risky than the method used by GRUB because a mis-configured LILO configuration file may leave the system unbootable (a popular way to fix this problem is to boot from Knoppix or another live CD, chroot into the partition with mis-configured lilo.conf and correct the problem). On the other hand, correcting a mis-configured GRUB is comparatively simple as GRUB will default to its command line interface where the user can boot the system manually. This flexibility is probably the main reason why many users nowadays prefer GRUB over LILO.
Unlike LILO, GRUB has a web site. It also has a manual, FAQ, a bug tracker, a developer mailing list and a logo. LILO has none of those.
lilo over grub
With more than a decade of development behind it, LILO is one of the most widely-used, well-tested and dependable Linux applications ever written. Most experienced system administrators are well-versed in configuring the LILO and skilled enough to deal with any emergency situation.
The Red Hat Linux Reference Guide claims that GRUB may have difficulties booting certain hardware. It does not provide any further details, though.
GRUB is, according to its developers, alpha-quality software. Use at your own risk.