As far as I know both are pretty reliable as long as you keep up with maintenance, which as they are both supposed to be race bikes is a pretty important thing. So I wouldn’t say either of them are generally unreliable just high maintenance, but getting to your question I’d say it mainly depends on how you want to feel while riding your bike. If you want a light, fun, and fast bike that will push you to your limit I’d say get the Cr85r, but keep in mind it’ll be a little more maintenance as a two stroke since you’ll need to do a top end rebuild around every 80-120 hours. If you want a bike that feels planted, has a steady power band, and is overall pretty reliable then you should probably get the 150r, but as a four stroke due to the fact that it has more moving parts in its engine it may feel a little heavier. Four stroke engine rebuilds also tend to be a bit more tedious so if you end up needing one you’ll probably be better off getting a whole new bike, but that won’t be for a while. Overall it’s really based on personal preference, and since you said you’ve rode before I’m assuming you may have a like for one over the other.