What are you wanting to do with your utility knife? On the utility side, I'm always a SAK fan. I carry more than one knife though. If I had to only have one, it would be a SAK...just for the utility. They are what I reach for most often. I have a micra on the keychain, but use it infrequently. I have a Spiderco that I rarely use. I've stopped carrying my Buck 110 (but still love the knife...sentimental I guess).

I do carry a SAK and a VIC Spirit. I also have one bigger rescue knife. But as mentioned above...the SAK is usually #1 and gets frequent daily use.