We've tested about every player there is out there, and while the Creative is an excellent machine, the iPod pips it (no Apple pun intended) for both sound and vision performance, and trounces it for usability. The Zen M is about to be discontinued, by the way, if that effects your decision (possibly in a positive way - there are bound to be big discounts around).
However, if it's mainly video you're after, the Creative Zen W is definitely worth a look, as it has a much larger screen than the Apple. We test both machines - and a host of other portable video solutions - in our September issue, on sale 23rd July.
A final word on the reliability you mention. MP3 players are relatively fragile beasts - especially the hard-disk based ones like the big iPod and the Creatives above. Drop them when they're working and you may have a dead player on your hands (however, Apple are excellent about replacing iPods if they're still under warranty).
The smaller-capacity players - like the iPod nano - are flash-memory based, so have no moving parts - less to go wrong, more durable in day-to-day use. So, you may consider sacrificing larger capacity/screen size for increased portability and durability. The choice is yours....