Different things... I like the multiband on ozone, and some othe cool stuff, nothing wrong with the maximizer. I use L2 in all my mixes at the master in order to get up the level and listen to the mix with some agressive compression that would be added later in the master, the mixes end up prepared for agressive master then and have a nice level to export as is to the client has a decent listening level. If you have to choose one, maybe ozone is more complete, has more options, then you could use the maximizer inside of it for this prupose, and you shouldn't have big difference... I use L2 and it works nice, is fast to set and not a heavy plugin at all. I've also used ozone wich is a bit heavier, takes some more time to set but it's also nice. As multiband I always like the ozone.
JS