If you go for a Magnum, I'd go for the Magnum 350 Deluxe at a minium. With the deluxe you get the quick release valves which makes maintenacne 10x easier!
If you have room for and want even better biological filtration then go for the Magnum 350 Pro. It is basically the Deluxe version plus dual bio wheels. It also makes cleaning the gravel easier. You can hook the gravel cleaning hose directly to the intake valve of the cannister filter. Then turn it on and you can take your time cleaning the gravel cuz its not actually removing the water from the tank but instead just passing the water through the cannister filter traping all the gunk! Then you just clean out the cannister! Very nice system for heavy filtration requirements imho