I don't know about the SOG Tomcat II, but in general I don't care much for SOG knives.
I think they're a bit expensive for what you get.
I don't like the CRKT Prowler than much because it's a liner-lock, which is my least preferred locking method.
And the AUS-6 is not all that great when it comes to edge-retention.
The Spyderco Polywog seems like a neat little knife, but it's just too small for me.
The Buck Alpha Hunter is nice but, again, it uses a liner-lock.
Not to mention the fact that it is a huge and heavy knife (even heavier than the Buck 110).
So that leaves the Delica 4.
But even the D4 is a little on the small side for my taste, so I would recommend the
Endura 4 instead.
Some other recommendations:
Benchmade 551 or 550 Griptilian for a nice general utility folder.
Spyderco Pacific Salt if you need something light-weight and don't mind a knife made in Japan.
Alaskan Guide Buck 110 from Cabelas if you don't mind a little bit of weight and no pocket-clip.
This is my current EDC and it is very nice.
Top-notch blade-steel on an American classic!:thumbup:
Buck Custom Shop 110 if you don't mind waiting about 6-8 weeks.
This is one that I'm waiting for right now.
Chris Reeve Sebenza if you've got money to burn and the desire to join a cult.
Good luck,
Allen.