Sounds a daft question and I know there are is a list of compatible trainers. But I’m looking to get a dumb trainer second hand and I’m wondering what would be the best to get. I’ve extensively Googled, YouTubed and scoured the forum but can’t find anything suitable already asked.
I already have a Wahoo Kickr Snap but I’m looking for a spare for when I’m working away and for the kids to try out Zwift alongside me.
Any recommendations would be appreciated.
TVM
Sean
The old Kurt Kinetics that I and my wife have owned, and several other people I know as well, always worked well. I had a Nashbar fluid trainer for a while that was inexpensive when new, but was solidly built.
In fact, Kurt had a version with a power meter in it. Not ‘smart’ in that it isn’t controllable, but it has power, BT at that, so it can be picked up by Zwift. Those would likely be cheap if you can find one second-hand.
Edit: they still make them, in fact. They a fully smart/controllable version too, but this one new is $300USD, so used could be a good deal.
Although…looking at their site, they have a direct drive trainer for $350USD. Did not know that.
Have you considered getting a tacx flow? Often not much more than dumb trainers. I have one, the power accuracy isn’t great but works nicely with zwift. Can pick them up second hand very cheaply of you shop around
Good advice from @Chris_Holton and @Tom_J as always.
The Kinetic Fluid go for cheap used and it is a good trainer, but it is jut a dumb trainer not controllable.
The tacx flow is a bit more expensive used but it is also controllable.
I picked my flow up from ebay for £70 and have used it as my back up for a few years now and I have a bit of a soft spot for it, it is a very capable trainer as long as you don’t need to rely on the power numbers to be too close
if you’re travelling then just get any old magnetic or fluid trainer… magnetic ones are usually lighter, fluid ones are nicer to ride on. kurt and elite make good fluid trainers
if you want something bombproof but weighs a ton or you need to sprint, then an elite muin (you can just remove the useless “smart” sensor), or a lemond revolution if you can find one.
The Saris Fluid2 has a power curve that they used to publish (Power vs Speed)…I probably still have the excel file around somewhere.
The KK will behave similarly but I do not recall ever having/getting the curve.
In general fluid trainers should be pretty repeatable, smooth, and reliable. The response is non-linear and mimics real life (but not quite exactly). Stay away from inexpensive magnetics. The response can be really bumpy and it is linear and does not feel “real”.
Elite Turno: fluid, direct-drive, power-meter built in, 700Watt max, butter smooth. Only IF you can find one cheaply, used.
4iiii Fliiiite would be another interesting one - it’s smart, interactive, wheel on and DEAD silent.
Others already suggested the Tacx Flow Smart which I have a soft spot for: I set a friend up with one and she loves it. Great value for money especially used. The Vortex Smart is its big brother. I’d sooner suggest these Tacx trainers than any fluid trainer relying on a “power curve” (like the Kurt Kinetic).
But the ‘fluid’ isn’t actually butter, right? 
I’ll add that the Kurt direct drive trainer I mentioned above is a power trainer–not smart (i.e. not controllable), but is wheel-off, seemingly portable, and has an ANT+/BT power meter, 700w max, +/-3% accuracy. For $350USD (no cassette at that price, but you can add an 11sp for I think $30). I only just discovered it myself, can’t offer a review, and I have a smart trainer so won’t be buying one, but it seems like a pretty good deal for that level/kind of trainer.
Both the Tacx Bushido and the Cycleops (now Saris) Powerbeam used to have power measurement of sorts and support ANT (the Bushido, like the modern Neo could also work without electricity).
Does your bike have a power meter? If so… rollers.