There isn't actually a big change in performance among any of these barrels, however, my least favorite among all of them is the J&J. It's not bad but I don't think it's as good as any of the others I listed.

I'll rate the barrels that can be used with the 98 for you. I own all of these barrels currently or did at one time.

#1: 14" Lapco Apex Ready .690 with Apex Tip. This is the same as a regular bigshot if you take the Apex tip off. I love this barrel. This is by far the most accurate barrel I have ever shot without the Apex. I also love the Apex and would recommend it to anyone who plays in the woods.

#2: 14" CP .693. This is a great barrel. For $30 this is a steal. I'll make this a tie with the CP .689 because they are the same barrel with different boring. I haven't used the .685.

#3: 14" PMI Razzor. They sell this for $15 on ANSgear for the 98. I have this as my backup for every gun that I own except my cocker threaded guns and that's only because I can't find a black cocker threaded one.

If you are trying a new barrel one day and it does one thing you don't like you'll always come crawling back to this one. I have had my Razzor barrel for my 98 for 6 years and I'll easily have it for another 6. Impressive barrel for $15.

#4: 14" Tippmann Sniper. Pretty good. Didn't "wow" me but it was alright.

#5: 16" Smart Parts Linear. It gets the job done. Nothing special here. $30 This is one of those things that lays in the closet forever. It's not that it's a bad barrel, it's just that I have so many that I like better.

#6: 12" J&J Ceramic. I personally was not impressed. It seemed like I just didn't have much better accuracy when I put this barrel on instead of the stock barrel. 

#7: 18" Opsgear Sniper. I got this back when I was a hardcore milsim player. It shoots okay but there is no porting at all so you get some unwanted spin sometimes. When I bought it, it was way overpriced. I don't know what it is now or if they even still sell it. It was $85 when I bought it.

#8: CMI Thunder Pig. Here is a barrel I flat-out don't like. To me it is like an elongated stock barrel. 

#9: The Flatline. I never used the platinum version of the flatline but in my experience, the first generation flatline was awful. You could shoot further but your accuracy was horrible. I know some people liked them but I, as they say, "couldn't hit the broad side of a barn with it."

#10: The stock barrel. No matter how bad any other barrel is you can always say it is an upgrade from the stock barrel. My opinion of the 98 custom stock barrel is something that Tippmann sticks on there to make you have to buy an upgrade.