I use both, although nowadays that's getting pricey. But if there was a third choice I'd probably buy that too. Neither is as accurate as you would want. It's simply not possible to experience conditions on every shift with every dealer, and hence you can only get a general idea no matter who you use.
CBJN has been around a long time, has a large experienced network of reporters, and is kept meticulously up-to-date. One downside is that pen reports are notoriously inaccurate. I was personally pretty upset when they jacked up the price an extra $30/year just because they chose to hire a couple new people. But that's just business and I still subscribe.
If you just got CBJN you'd be pretty happy. I used it for years and made a lot of money with it.
Trackjack is the digital reincarnation of the Blackjack Forum which is both good and bad. The good part is that Snyder's reporters tend to look at things with a slightly more professional eye, the bad part is the penetration codes are a bit too vague to really plan your play around (e.g. create customized indices, SCORE your sessions, etc.). It's a common complaint, and when I emailed Viktor he replied that they were working on something totally new for pen, so hopefully that will get better.
I almost didn't subscribe because during the beta test there were almost 0 updates, but they also recently hired a full-time editor. I don't know how much they're paying this guy, or if he eats or sleeps, but he's making updates to conditions reports almost 24 hours a day. I think they're using all their old Blackjack Forum reporters and hiring a bunch of new ones.
They have a search engine that lets you define your favorite game and tells who has it, and other players post their comments and stuff. One big difference is that anyone can contribute reports to Trackjack.
Again, when it comes to the core data, you could get by with either. But these days I use Trackjack to find my kinds of games and then I cross-reference CBJN to get as broad a view as possible of what I'm up against. I think Trackjack is really exciting and proving increasingly accurate, but CBJN is still the comfortable fall-back.
You should try them both. Each is about $20 for 3 months . It would probably be worth it to see which worked for you. Trackjack is about $30 cheaper for a whole year, but if you play enough, the price difference won't matter.
for in-accurate pen notations in CBJN might be because whenever a report is made on any venue in a metro area, CBJN updates the date for the entire metro area to the current month. As an example (not necessarily accurate), if a report came in on Nooksack (near Bellingham) but not on Swinomish, the date for Bellingham would be updated to the current month even though the Swinomish info could be quite dated.
I would like to see CBJN date each venue rather than each metro area.
I found CBJN reports for venues that are reported frequently to show pen quite accurately and have been very pleased with it's Nevada reporting.