This may not be much help, as I've only messed around with fiberglass resin a little, and have only read the literature for Aqua-Resin. Fiberglass resin will definitely be cheaper - a quart of resin and hardener is around $15, while the half-pint AR trial kit is $30, plus shipping if you don't have a local distributor.
Easier to use I can't speak to, but fiberglass resin is pretty simple to mix and apply. You need to work quickly, but 5-10 minutes is plenty of time if you've laid out your materials beforehand. Aqua-resin cures slower, 30 minutes to 2 hours, depending on the mix ratio. It can also be mixed up thinner or thicker, depending on what you're using it for. Fiberglass resin can be thickened by adding Bondo (to make "Rondo").
Best results is really up to you - I think either material will work well if you put in the time and effort. The main advantage of Aqua-Resin is the lack of fumes, so it can be used indoors with little to no ventilation. Fiberglass resin needs to be used outside, or in a very-well ventilated area, preferably not open to main living areas. I don't find the smell offensive, but others do, and the fumes are fairly toxic while it cures.
Other opinions? I'm very curious about Aqua-Resin, as I don't have a garage, and it gets too cold to work outside here for 5-6 months of the year. (Aqua-Resin is
this stuff, for those who haven't seen it before.)