Trainers and resistance

If it's just those two choices, I'd pick #2. Assuming you'll last longer with #2, low resistance but high cadence. To me, that's sort of like building base or working on technique.

#1 to me is like hills or intervals, you are just building strength. You won't be able to do it too long.

To me, the best of course is a combination of both.

A mag. trainer will provide you linear resistance, not progressive like a fluid or a wind trainer. So the resistance you get with the first spin is what you get with the later ones. This means that if you are spinning the big gear with the hardest setting, you are riding like you would pushing a big gear on the street (intervals/hills). If you were doing that on a wind/fluid trainer and decided to pick up the pace, it would actually give you more resistance making it even harder to maintain.

The two options you gave are completely different types of workouts. This early in the season/off season, it is a much better idea to spin an easier gear at 90 - 100 cadence for a long time keeping your heart rate down in the aerobic zone than it is to mash a big gear with heavy resistance.

It is always good to remember that explosive speed and strength is one of the last things you develop in a training cycle as it is one of the fastest things to diminish. What you should focus on imho is the base aerobic fitness as this sticks with you throughout the entire season and reaps the most benefits in the long term.

Just my worthless opinion .....

if you can afford mag you can splurg a little and get the fluid