I think both TB and TT are very Oakley. They just relate to the brand image at their respective eras.
TimeBomb was out at a time where X-Metals were at their birth stage, especially Mars at that same year (1998). That year also saw the introduction of Racing Jacket and Moon, two other ''Overthetop'' creations. TimeBomb was probably the Oakley-est product they made at that time, along with Romeo, Overthetop, Juliet, XX...some people refer to these styles as if they come ''from outer space''...
TimeTank came out this year, along with models like Eyepatch, O ROKR, Oil Drum, Gascan S...all models that scream industrial, but with a trendy look that identify very well with the streets, the high class, and the dominant figure of having something ''big'' : big SUV, big rims, big watch. So at this era and stage of the company, yes, TimeTank is probably the product that fits Oakley the most, along with Thump Pro, in my opinion.
That being said, I don't think you should make your choice based on ''which one says more Oakley?'', unless you're looking for ''which one is the most Oakley-est NOW?'' Of course, anybody feel free to disagree with my perspective on the matter, but being a long-term Oakley fan and now employee, who gets a lot of updates on company target markets, objectives, and such...I don't think I'm far off the line in my argument.
5 years ago, the coolest time piece to rock with a Mars was probably the TimeBomb. Today, the TimeTank is probably way more appropriate to wear with your White Oil Drum with Diamond-encrusted icons !
Fook it, who am I kidding, buy both and let's lock this thread ! hahaha just kidding.
Finally though, if both appeal to you, go with most other people's logic concerning availability. The more you wait, the harder and the more expensive it will be to get a TB. TimeTank came out THIS year. You still have plenty of time to get it in the future, and who knows, we might see some new colors, maybe even a limited edition ???