*ramble alert*
It seems to have changed over time what is the "good" choice, depends on situation.
My first win was at level 30 on the first sunday of a TBC launch server, and the trinket was very handy leveling in certain zones. I wore it full-time for many levels due to the general lack of solo quest trinkets. It was also awesome to go fishmode in town (TB pond) and whenever else I could in groups or raids like SSC :)
I won again at level 49 the next sunday for the pole, but it was awhile before I had the "free time" (level 70 and clearing karazhan, waiting for 25 people geared enough for gruul) to skill up and equip it.
Before the contest was associated with achievements/title seekers, only fishing nuts or OCDs did it with any seriousness. It was pretty slow and quiet on the various servers I did it on, I felt no real pressure, had no harassment at all and enjoyed winning the contest on a couple more characters as well.
3.0 sure did change that, I absolutely hate the contest now and don't know what demon made me do it on my DK and new druid. Probably the same demon making me finish 3 more purple protos in July and the 7th in Oct. (I really hate brewfest, and slow flightpaths in general)
Before they changed how fishing skill worked, the pole was a no-brainer except for rare situations like my first. Now that skill means very little (almost everything you want is in pools) its a toss-up to your vanity or perfectionism.
+10 skill that rarely matters versus the easy to get jeweled pole that looks so much better on many characters, and you can drag the trinket out of the bank to play in the fountain. They really should update the pole graphic...