When I bought my smart trainer I only had a mtb. Now I have a road bike with power too.
I’m thinking about just getting some Kreitler rollers and using my road bike on it for the days when the wind has 50 mph gusts, or it’s just torrential rain.
I know I’ll be missing out on erg mode, and watching movies on my iPad, but I think the training might be better(?)
Thoughts?
Depends on how much you value erg mode and structured indoor rides. Personally I get more watts per dollar out of TR and indoor training than any other purchase i could make. If you do to just spend those few hundred euro and get a new trainer. Or try get your current one fixed or go 2nd hand.
I have no experience with rollers but I assume you cant do threhold effords very effectively?
Smart trainers are dime a dozen on FB marketplace these days. In the Denver area I have found four or five Kickr Cores for under $350. Which, not knowing budget could be high or low. I only know this as I was searching for a while for a replacement to my gen 2 kickr as it felt horrible. I finally did the advanced spin down and it seemed to fix it.
Rollers would work, but they can be pretty limiting in terms of how much power you can put out. It gets pretty tough to do much more than Z2 on most rollers.
A “normal” trainer might be a good alternative. Fluid trainers work great, and some fluid trainers are even direct-drive like smart trainers are these days (just without the “smart” bit).
Kreitlers aren’t exactly “cheap” rollers, either, so it may even be worth just fixing/replacing the trainer that died. 
Define “better”.
You will arguably be more engaged as you really can’t let your mind wander much. You’ll also likely pick up some handling / balance skills over time (I got to the point where I could take my jersey on and off while riding rollers, among other stupid tricks).
One of the limiters of rollers tends to be higher wattage intervals…for some rollers, you’ll simply spin out before hitting the wattage you want / need. For those that can provide enough resistance, getting those numbers can be challenging from a handling perspective for some.
Id be wary of high power sprints on rollers but @Jonathan uses rollers all the time and they are probably more interesting for other work.
If you are considering cheap rollers, then there are limitations on resistance. If you are willing to spend a bit, rollers do everything a smart trainer does while providing a much better ride dynamic. You can go with manual resistance or smart resistance just like a trainer. I’ve been using e-motion rollers for all my indoor training for almost 15 years, upgraded to the smart version several years ago. No issue doing intervals at any power level. Great for zwift, climbing out of saddle, etc. Just a much better riding experience in my opinion, I hate fixed trainers. Rollers have a learning curve, but it’s short.
I use Kreitler rollers, I would imagine most rollers with a small enough drum would offer the same benefits. I snapped a band on one, and a replacement was there in a matter of days.
Personally have really enjoyed the rollers, I’ve yet to require more resistance than what the rollers give me. 300ftp/64kg for reference, done all my interval training on them.
Great for core stability, great for pedalstroke, great for actually judging how hard to push to reach a specified power. ERG is the devil.
I’ve come from 2+years of knee injuries, which wasn’t being helped by the trainer, which i felt allowed me to just pedal squares.
Easy to set up, easy to pack away. Keeps you a little occupied, especially with boring Z2 rides. I tend to do single leg drills during the warmups too 
If a set of rollers can’t get enough power, it’s easy to add magnetic resistance, assuming a metal roller. Get some neodymium magnets with countersunk holes, screw them to a piece of wood, and fix that to the rollers so there is a small gap between the magnets and the roller.
I use InsideRide rollers with the smart module and love them, I haven’t touched my fixed trainer this whole winter season. I do workouts and Zwift races on them, and can get up around 900w in sprints (probably my limitation and not the rollers). They definitely seem to be love it or hate it though. I know plenty of people who do a few rides and sell them. But I’ve gotten to the point where 0% of my energy goes into staying on them, it’s just natural to ride.