What are some recommendations for a trainer to get better at going uphill?
Whilst it is true that there are some differences in muscle recruitment between pedalling uphill and on the flat, the main difficulty hills present is an increased power output for a sustained period of time (unless you have a tiny gear of course).  However the main factor it comes down to is fitness - pure power/weight ratio - 200W is still 200W whether its uphill/flat/downhill. 

Riders that struggle with hills tend to fall into one (or both) of two categories


Heavy riders that are held back by their weight and lack the muscular endurance to sustain a high power output over a long period
Weaker riders who lack the raw leg power to push the pedals round.


Any of the trainers you mentioned should be fine for your needs - find workouts that work on either improving your lactate threshold, or improving the force you can apply to the pedals at low cadence.
If you want to more closely mimic hill climbing, then put your front wheel on a tall riser block, ride with your hands on the tops of the bars, and concentrate on pedalling smoothly from the hips.

For reference, I use the Fluid² you mentioned, and have seen good gains over the last 12 months doing 2-4 minute big gear intervals (60rpm) to build leg strength and get used to applying force smoothly.