smallbitSorry, but there is no option for purchasing the Rocketeer without the keycaps. The keycaps and the case go together, and while there is a little bit of assembly to do yourself (installing the switches and keycaps), this is not a DIY keyboard intended to be purchased for its separate parts.
smallbitThat really comes down to personal preference. I've not used either (yet), so I'd have to base my choice on what others have reported. And on that score, I'd go with Halo Trues. In fact, I went in on a recent drop for a whole bag of them to try with this keyboard. I chose Trues because people described them as being more like Topre switches in general feel than Clears, and that's what I would prefer. But that might not be what you're looking for. ¯\_(ツ)_/¯
smallbitThe dilemma of Too Many Good Choices!
The one saving grace here is that thanks to the hotswap PCB, you can try different switches with minimal effort. The only pain will be to your wallet!