Meanwhile I have around 40 Spydies. In general my preference is for European knives, except for Spydercos - I love many of them.
My recommendations:
For midsize knives:
- Considering you have a slipjoint background, you owe it to yourself to try a UKPK. It's a great knife, and if you'd want something cheaper, well a more midrange and much cheaper variant will come out in a few months.
- If you'd prefer a locking Spydie in that size then have a look at the Caly 3 (very similar to UKPK except for the lock) if you like backlock or the Sage if you like a great liner lock. Delica is nice, and I think that Caly is something else still.
For bigger models:
- have a look at the excellent slicer that is the Chokwe. It is actually much better in the hand than you'd expect when seeing it.
- The Centofante 3 is also a superb slicer, one of Spydercos best ones in fact and it's pretty affordable.
- Eventually you'll want a Military. They're all great!
- you can still find the special Volpe if you search around - it's lovely I think.
For smaller knives: interesting to know is that Kiwis and Kopas are being discounted. Both are excellent, I prefer the Kiwi, others may prefer the Kopa.
The Urban is a great smaller slipjoint, the small brother of the UKPK. I have the wharncliffe one. Lovely and it won't scare too many people.
I will finish with one particular model that is perhaps the one of all my Spydies I would select if i could only have one: the Stretch 2. I have the CF version, the cheaper FRN handled one should be great too. The ZDP steel ones have a flat grind. I think it offers the perfect combination of qualities.
Watch out with the ZDP steel: it's very hard so don't let it get dull between (rare) sharpenings and keep in mind it's only just stainless so wipe it dry after use.