If i ever get the cash to get myself a custom, i'll keep whatever the first may be. It will probably be a custom 110 as a user version of my first real knife (a 110 knock off, given to me by my dad and engraved by him, which i'll also be keeping) or a Puukko, seeing as i'm half Finnish.
I also may end up keeping my Victorinox alox Farmer, just because it seems to be the toughest most useable SAK ever. Farmers have everything i'd need in a SAK and nothing i don't. It sees alot more use than my one handers and even seems a little more useful in the bush than my fixed blades or one handers. I've had it engraved with my nickname and it's well suited to city carry, which is good seeing as i'm moving in May and doesn't seem to bother folks.
I'll also keep a few old handmade knives by a friend of the family who used to look after me as a child, he has since passed on ( in 97). But he left behind some wonderful oldschool razor sharp pieces. I wouldn't be surprised if they were made during or just after world war two.