Do you mean "collecting" as in buying a knife that will sit in a safe, or do you plan to actually carry and use it?
Any of the choices listed here would be excellent first Spydercos as users, as for being true "collectibles," not so much.
I think that you would best be served by finding a Brick and Mortar Spyderco dealer and putting your hands on some. You'll know when you find the one that's right for you--to get things started.
It's not uncommon for your tastes to change. I got a Dragonfly and was really impressed with it, so I picked up a Delica. I loved the Delica, and it kicked a lot of other knives out of my pocket. That wasn't the plan, but that's how it's gone. I saw people here just rave about the PM2, but I thought it was a tad big for my use. Well, a finally got a PM2, and yes, I love it as well. It's more a weekend/outdoors/heavy use knife for me. The Delica spends a lot of time in my pocket during the week. It's never caused anybody to look twice when I take it out and use it, and it's more than up to the tasks I need for the work week.
So enjoy the hunt, it's more than half the fun, and for many people here it never really ends. Once you find a knife you like--then you can consider getting into the Sprint Runs, and that's when the true "collecting" side of this starts. To get to that point, you're best served finding a model--or models-- you really like.